Question: Who is the mother of the leader that helped the empire where the principate was formed reach its greatest extent?

full_context: Document 1: Middle Ages: The Emperor Diocletian (r. 284–305) split the empire into separately administered eastern and western halves in 286; the empire was not considered divided by its inhabitants or rulers, as legal and administrative promulgations in one division were considered valid in the other.[C] In 330, after a period of civil war, Constantine the Great (r. 306–337) refounded the city of Byzantium as the newly renamed eastern capital, Constantinople. Diocletian's reforms strengthened the governmental bureaucracy, reformed taxation, and strengthened the army, which bought the empire time but did not resolve the problems it was facing: excessive taxation, a declining birthrate, and pressures on its frontiers, among others. Civil war between rival emperors became common in the middle of the 4th century, diverting soldiers from the empire's frontier forces and allowing invaders to encroach. For much of the 4th century, Roman society stabilised in a new form that differed from the earlier classical period, with a widening gulf between the rich and poor, and a decline in the vitality of the smaller towns. Another change was the Christianisation, or conversion of the empire to Christianity, a gradual process that lasted from the 2nd to the 5th centuries.
Document 2: Salonia Matidia: Salonia Matidia (4 July 68 CE – 23 December 119 CE) was the daughter and only child of Ulpia Marciana and wealthy praetor Gaius Salonius Matidius Patruinus. Her maternal uncle was the Roman emperor Trajan. Trajan had no children and treated her like his daughter. Her father died in 78 CE and Matidia went with her mother to live with Trajan and his wife, Pompeia Plotina.
Document 3: Roman Republic: The extensive campaigning abroad by Roman generals, and the rewarding of soldiers with plunder on these campaigns, led to a general trend of soldiers becoming increasingly loyal to their generals rather than to the state. Rome was also plagued by several slave uprisings during this period, in part because vast tracts of land had been given over to slave farming in which the slaves greatly outnumbered their Roman masters. In the 1st century BC at least twelve civil wars and rebellions occurred. This pattern continued until 27 BC, when Octavian (later Augustus) successfully challenged the Senate's authority, and was made princeps (first citizen).
Document 4: Roman Republic: The Roman Republic (Latin: Res publica Romana; Classical Latin: [ˈreːs ˈpuːb.lɪ.ka roːˈmaː.na]) was the period of ancient Roman civilization beginning with the overthrow of the Roman Kingdom, traditionally dated to 509 BC, and ending in 27 BC with the establishment of the Roman Empire. It was during this period that Rome's control expanded from the city's immediate surroundings to hegemony over the entire Mediterranean world. During the first two centuries of its existence, the Roman Republic expanded through a combination of conquest and alliance, from central Italy to the entire Italian peninsula. By the following century, it included North Africa, Spain, and what is now southern France. Two centuries after that, towards the end of the 1st century BC, it included the rest of modern France, Greece, and much of the eastern Mediterranean. By this time, internal tensions led to a series of civil wars, culminating with the assassination of Julius Caesar, which led to the transition from republic to empire. The exact date of transition can be a matter of interpretation. Historians have variously proposed Julius Caesar's crossing of the Rubicon River in 49 BC, Caesar's appointment as dictator for life in 44 BC, and the defeat of Mark Antony and Cleopatra at the Battle of Actium in 31 BC. However, most use the same date as did the ancient Romans themselves, the Roman Senate's grant of extraordinary powers to Octavian and his adopting the title Augustus in 27 BC, as the defining event ending the Republic.
Document 5: Fall of the Western Roman Empire: Relevant dates include 117 CE, when the Empire was at its greatest territorial extent, and the accession of Diocletian in 284. Irreversible major territorial loss, however, began in 376 with a large - scale irruption of Goths and others. In 395, after winning two destructive civil wars, Theodosius I died, leaving a collapsing field army and the Empire, still plagued by Goths, divided between his two incapable sons. By 476 when Odoacer deposed the Emperor Romulus, the Western Roman Emperor wielded negligible military, political, or financial power and had no effective control over the scattered Western domains that could still be described as Roman. Invading barbarians had established their own power in most of the area of the Western Empire. While its legitimacy lasted for centuries longer and its cultural influence remains today, the Western Empire never had the strength to rise again.
Document 6: Roman Empire: The Roman Empire (Latin: Imperium Rōmānum, Classical Latin: (ɪmˈpɛ. ri. ũː roːˈmaː. nũː); Koine and Medieval Greek: Βασιλεία τῶν Ῥωμαίων, tr. Basileia tōn Rhōmaiōn) was the post-Roman Republic period of the ancient Roman civilization, with a government headed by emperors and large territorial holdings around the Mediterranean Sea in Europe, Africa and Asia. The city of Rome was the largest city in the world c. 100 BC -- c. AD 400, with Constantinople (New Rome) becoming the largest around AD 500, and the Empire's population grew to an estimated 50 to 90 million inhabitants (roughly 20% of the world's population at the time). The 500 - year - old republic which preceded it had been severely destabilized in a series of civil wars and political conflict, during which Julius Caesar was appointed as perpetual dictator and then assassinated in 44 BC. Civil wars and executions continued, culminating in the victory of Octavian, Caesar's adopted son, over Mark Antony and Cleopatra at the Battle of Actium in 31 BC and the annexation of Egypt. Octavian's power was then unassailable and in 27 BC the Roman Senate formally granted him overarching power and the new title Augustus, effectively marking the end of the Roman Republic.
Document 7: 1st century: During this period, Europe, North Africa and the Near East fell under increasing domination by the Roman Empire, which continued expanding, most notably conquering Britain under the emperor Claudius (AD 43). The reforms introduced by Augustus during his long reign stabilized the empire after the turmoil of the previous century's civil wars. Later in the century the Julio - Claudian dynasty, which had been founded by Augustus, came to an end with the suicide of Nero in AD 68. There followed the famous Year of Four Emperors, a brief period of civil war and instability, which was finally brought to an end by Vespasian, ninth Roman emperor, and founder of the Flavian dynasty. The Roman Empire generally experienced a period of prosperity and dominance in this period and the First Century is remembered as part of the Empire's golden age.
Document 8: Roman conquest of the Iberian Peninsula: The Roman conquest of Hispania was a process by which the Roman Republic seized the Carthaginian territories in the south and east in 206 BC (during the Second Punic War) and then gradually extended control over most of the Iberian Peninsula without annexations. It was completed after the fall of the Republic (27 BC), by Augustus, the first Roman emperor, who annexed the whole of Hispania to the Roman Empire in 19 BC. Hispania was the Roman name for the Iberian Peninsula. The peninsula had various ethnic groups and a large number of tribes.
Document 9: Trajan: As a civilian administrator, Trajan is best known for his extensive public building program, which reshaped the city of Rome and left numerous enduring landmarks such as Trajan's Forum, Trajan's Market and Trajan's Column. Early in his reign, he annexed the Nabataean Kingdom, creating the province of Arabia Petraea. His conquest of Dacia enriched the empire greatly, as the new province possessed many valuable gold mines.
Document 10: History of the Constitution of the Late Roman Empire: The History of the Constitution of the Late Roman Empire is a study of the ancient Roman Empire that traces the progression of Roman political development from the abolition of the Roman Principate around the year 200 until the fall of the Western Roman Empire in 476 CE. When Diocletian became Roman Emperor in 284 CE, he inherited a constitution that was no longer functioning, and so he enacted the most significant constitutional reforms in over three-hundred years. His reforms, much like those three-hundred years before, were intended to correct the errors in the previous constitution. Diocletian's specific reforms were less radical than was the reality that he exposed the state of government for what it had been for centuries: monarchy. With Diocletian’s reforms the Principate was abolished, and a new system, the Dominate (Latin: "lord" or "master"), was established.
Document 11: Trajan: Marcus Ulpius Traianus was born on 18 September 53AD in the Roman province of Hispania Baetica (in what is now Andalusia in modern Spain), in the city of Italica (now in the municipal area of Santiponce, in the outskirts of Seville). Although frequently designated the first provincial emperor, and dismissed by later writers such as Cassius Dio (himself of provincial origin) as "an Iberian, and neither an Italian nor even an Italiot", Trajan appears to have hailed on his father's side from the area of Tuder (modern Todi) in Umbria, at the border with Etruria, and on his mother's side from the Gens Marcia, of an Italic family of Sabine origin. Trajan's birthplace of Italica was founded as a Roman military colony of "Italian" settlers in 206BC, though it is unknown when the Ulpii arrived there. It is possible, but cannot be substantiated, that Trajan's ancestors married local women and lost their citizenship at some point, but they certainly recovered their status when the city became a municipium with Latin citizenship in the mid-1st century BC.
Document 12: Roman mythology: The Aeneid and Livy's early history are the best extant sources for Rome's founding myths. Material from Greek heroic legend was grafted onto this native stock at an early date. The Trojan prince Aeneas was cast as husband of Lavinia, daughter of King Latinus, patronymical ancestor of the Latini, and therefore through a convoluted revisionist genealogy as forebear of Romulus and Remus. By extension, the Trojans were adopted as the mythical ancestors of the Roman people.
Document 13: Diocletianic Persecution: The Diocletianic or Great Persecution was the last and most severe persecution of Christians in the Roman Empire. In 303, the Emperors Diocletian, Maximian, Galerius, and Constantius issued a series of edicts rescinding the legal rights of Christians and demanding that they comply with traditional Roman religious practices. Later edicts targeted the clergy and ordered all inhabitants to sacrifice to the Roman gods (a policy known as universal sacrifice). The persecution varied in intensity across the empire -- weakest in Gaul and Britain, where only the first edict was applied, and strongest in the Eastern provinces. Persecutory laws were nullified by different emperors at different times, but Constantine and Licinius's Edict of Milan (313) has traditionally marked the end of the persecution.
Document 14: Roman Republic: The Roman Republic (Latin: Res publica Romana; Classical Latin: (ˈreːs ˈpuːb. lɪ. ka roːˈmaː.na)) was the era of ancient Roman civilization beginning with the overthrow of the Roman Kingdom, traditionally dated to 509 BC, and ending in 27 BC with the establishment of the Roman Empire. It was during this period that Rome's control expanded from the city's immediate surroundings to hegemony over the entire Mediterranean world.
Document 15: Roman Empire: The imperial period of Rome lasted approximately 1,500 years compared to the 500 years of the Republican era. The first two centuries of the empire's existence were a period of unprecedented political stability and prosperity known as the Pax Romana, or ``Roman Peace ''. Following Octavian's victory, the size of the empire was dramatically increased. After the assassination of Caligula in AD 41, the Senate briefly considered restoring the republic, but the Praetorian Guard proclaimed Claudius emperor instead. Under Claudius, the empire invaded Britannia, its first major expansion since Augustus. After Claudius' successor, Nero, committed suicide in AD 68, the empire suffered a series of brief civil wars, as well as a concurrent major rebellion in Judea, during which four different legionary generals were proclaimed emperor. Vespasian emerged triumphant in AD 69, establishing the Flavian dynasty, before being succeeded by his son Titus, who opened the Colosseum shortly after the eruption of Mount Vesuvius. His short reign was followed by the long reign of his brother Domitian, who was eventually assassinated. The Senate then appointed the first of the Five Good Emperors. The empire reached its greatest extent under Trajan, the second in this line.
ground_truth: Marcia
sub_queries: principate >> country Answer: Roman Empire
when did Roman Empire reach its greatest extent Answer: under Trajan
Who is under Trajan 's mother? Answer: Marcia