Please answer the following question: Information: - The Hazarajat (also referred to as Hazaristan) is a regional name for the territory inhabited by the Hazara people, which lies in the central highlands of Afghanistan, among the Koh-i-Baba mountains and the western extremities of the Hindu Kush. Its physical boundaries are roughly marked by Bamiyan to the north, the headwaters of the Helmand River to the south, Firuzkuh in Ghor to the west, and the Unai Pass to the east. "Hazrajt denotes an ethnic and religious zone rather than a geographical onethat of Afghanistan's Turko-Mongol Shiites." - Kandahar or Qandahar (, Persian: , , known in older literature as Candahar) is the second-largest city in Afghanistan, with a population of about 491,500 . Formerly called Alexandria Arachosia, the city is named after Alexander the Great, who founded it in 329 BC around a small ancient Arachosian town. Kandahar is the capital of Kandahar Province, located in the south of the country at an altitude of 1,010 m above sea level. The Arghandab River runs along the west of the city. The city of Kandahar has a population of 557,118. It has 15 districts and a total land area of 27,337 hectares. The total number of dwellings in Kandahar is 61,902. - Afghanistan (Pashto/Dari: , "Afnistn"), officially the Islamic Republic of Afghanistan, is a landlocked country located within South Asia and Central Asia. It has a population of approximately 32 million, making it the 42nd most populous country in the world. It is bordered by Pakistan in the south and east; Iran in the west; Turkmenistan, Uzbekistan, and Tajikistan in the north; and China in the far northeast. Its territory covers , making it the 41st largest country in the world. - Iran (, also , ; ' ), also known as Persia, officially the Islamic Republic of Iran (' ), is a sovereign state in Western Asia. It is bordered to the northwest by Armenia, the "de facto" Nagorno-Karabakh Republic, and Azerbaijan; to the north by the Caspian Sea; to the northeast by Turkmenistan; to the east by Afghanistan and Pakistan; to the south by the Persian Gulf and the Gulf of Oman; and to the west by Turkey and Iraq. Comprising a land area of , it is the second-largest country in the Middle East and the 18th-largest in the world. With 82.8 million inhabitants, Iran is the world's 17th-most-populous country. It is the only country with both a Caspian Sea and an Indian Ocean coastline. The country's central location in Eurasia and Western Asia, and its proximity to the Strait of Hormuz, make it of great geostrategic importance. Tehran is the country's capital and largest city, as well as its leading economic center. - Pakistan (or ), officially the Islamic Republic of Pakistan, is a federal parliamentary republic in South Asia on crossroads of Central Asia and Western Asia. It is the sixth-most populous country with a population exceeding 200 million people. It is the 36th largest country in the world in terms of area with an area covering . Pakistan has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by India to the east, Afghanistan to the west, Iran to the southwest and China in the far northeast respectively. It is separated from Tajikistan by Afghanistan's narrow Wakhan Corridor in the north, and also shares a maritime border with Oman. - The Baba Mountain range ("Baba ar"; "Koh-e Baba") is the western extension of the Hindu Kush, and the origin of Afghanistan's Kabul, Helmand, Arghandab and the Hari River. The mountain range is crowned by Foladi peak ("Shah Fuladi") rising 4951 m; 16,244 ft. above sea level, and is located south of Bamyan, Afghanistan. - Khost or Khowst (Pashto/Persian: ) is a city in eastern Afghanistan. Khost is a mountainous region near Pakistan's border with neighboring North Waziristan in the Federally Administered Tribal Areas and Bannu in Pakistan. The population of Khost City is about 160,000 people and the whole province has around a million. There are various tribes living in Khost. Some of the main tribes are Zadran, Mangal, Zazi, Tani, Gurbaz, Muqbal, and Sabari. The city of Khost has a population of 106,083 (in 2015). it has 6 districts and a total land area of 7,139 Hectares. The total number of dwellings in this city are 11,787. - The Hindu Kush (Pashto, Persian and ), also known in Ancient Greek as the Caucasus Indicus or Paropamisadae, is an mountain range that stretches near the Afghan-Pakistan border, from central Afghanistan to northern Pakistan. It forms the western section of the "Hindu Kush Himalayan Region" ("HKH"). It divides the valley of the Amu Darya (the ancient "Oxus") to the north from the Indus River valley to the south. - The First Anglo-Afghan War (also known as the great disaster) was fought between British imperial India and the Emirate of Afghanistan from 1839 to 1842. Initially, the British successfully intervened in a succession dispute between pro-Russian emir Dost Mohammad (Barakzai) and former emir Shah Shujah (Durrani), whom they installed upon conquering Kabul in August 1839. However, in 1841 the Army of the Indus, numbering between 24,000 and 28,000 including families of soldiers, military and political pundits, suffered a series of defeats at the hands of rebel Afghan tribesmen. The main British Indian and Sikh force occupying Kabul, having endured harsh winters as well, was almost completely annihilated while retreating in January 1842. It was one of the first major conflicts during the Great Game, the 19th century competition for power and influence in Central Asia between Britain and Russia. - Ariana, the Latinized form of the Ancient Greek "Ar(e)ian" (inhabitants: ""; "Ar(e)ianoi"), was a general geographical term used by some Greek and Roman authors of the ancient period for a district of wide extent between Central Asia and the Indus River, comprehending the eastern provinces of the Achaemenid Empire that covered the whole country of modern day Afghanistan, and a few parts of Pakistan, Tajikistan, Iran, Turkmenistan, and Uzbekistan. - Turkmenistan (or ); formerly known as Turkmenia is a country in Central Asia, bordered by Kazakhstan to the northwest, Uzbekistan to the north and east, Afghanistan to the southeast, Iran to the south and southwest, and the Caspian Sea to the west. - Unai Pass (el. 3000 m.) traverses the Sanglakh Range, an offshoot of the Hindukush, west of Kabul. It is the main road connection of Kabul with Hazarajat. - South Asia or Southern Asia is a term used to represent the southern region of the Asian continent, which comprises the sub-Himalayan SAARC countries and, for some authorities, adjoining countries to the west and east. Topographically, it is dominated by the Indian Plate, which rises above sea level as Nepal and northern parts of India situated south of the Himalayas and the Hindu Kush. South Asia is bounded on the south by the Indian Ocean and on land (clockwise, from west) by West Asia, Central Asia, East Asia, and Southeast Asia. - Pashto (; "Paxt" ), also known in older literature as Afghn or Pahn, is the South-Central Asian language of the Pashtuns. Its speakers are called Pashtuns or Pukhtuns and sometimes Afghans or Pathans. It is an Eastern Iranian language, belonging to the Indo-European family. Pashto is one of the two official languages of Afghanistan, and it is the second-largest regional language of Pakistan, mainly spoken in the west and northwest of the country. Pakistan's Federally Administered Tribal Areas (FATA) are almost 100% Pashto-speaking, while it is the majority language of the province of Khyber Pakhtunkhwa and the northern districts of Balochistan. Pashto is the main language among the Pashtun diaspora around the world. The total number of Pashto-speakers is estimated to be 4560 million people worldwide. - Central Asia or Middle Asia is the core region of the Asian continent and stretches from the Caspian Sea in the west to China in the east and from Afghanistan in the south to Russia in the north. It is also colloquially referred to as "the 'stans" (as the six countries generally considered to be within the region all have names ending with the Persian suffix "-stan", meaning "land of") and is within the scope of the wider Eurasian continent. - The Indus River, also called Darya-e-Sindh or Sindh River or Absn, is a major south-flowing river in South Asia. The total length of the river is which makes it one of the longest rivers in Asia. Originating in the western part of Tibet in the vicinity of Mount Kailash and Lake Manasarovar, the river runs a course through Ladakh, Gilgit-Baltistan, and Khyber Pakhtunkhwa, and then flows along the entire length of Punjab to merge into the Arabian Sea near the city of Thatta in Sindh. It is the longest river of Pakistan. - The Helmand River (also spelled "Helmend, Helmund, Hirmand"; Pashto/Persian: ', Greek: ' ("Etymandros"), Latin: "") is the longest river in Afghanistan and the primary watershed for the endorheic Sistan Basin. - Arachosia is the Hellenized name of an ancient satrapy in the eastern part of the Achaemenid, Seleucid, Parthian, Greco-Bactrian, and Indo-Scythian empires. Arachosia was centred on Arghandab valley in modern-day southern Afghanistan, and extended east to as far as the Indus River in modern-day Pakistan. The main river of Arachosia was called "Arachtos", now known as the Arghandab River, a tributary of the Helmand River. The Greek term "Arachosia" corresponds to the Aryan land of "Harauti" which was around modern-day Helmand. The Arachosian capital or metropolis was called Alexandria Arachosia or Alexandropolis and lay in what is today Kandahar in Afghanistan. Arachosia was a part of the region of ancient Ariana. - Arghandab is a river in Afghanistan , about 400 km ( 250 mi ) in length . It rises in the Hazarajat country north - west of Ghazni , and flows south - west falls into the Helmand 30 km ( 19 mi ) below Girishk . In its lower course it is much used for irrigation , under the control of the Helmand and Arghandab Valley Authority , and the valley is cultivated and populous ; yet the water is said to be somewhat brackish . It is doubtful whether the ancient Arachotus is to be identified with the Arghandab or with its chief confluent the Tarnak , which joins it on the left out 50 km ( 31 mi ) SW of Kandahar . The Tarnak , which flows south of Kandahar , is much shorter ( length about 320 km or 200 miles ) and less copious . The ruins at Ulan Robat , supposed to represent the city Arachosia , are in its basin ; and the lake known as Ab - i - Istada , the most probable representative of Lake Arachotus , is near the head of the Tarnak , though not communicating with it . The Tarnak is dammed for irrigation at intervals , and in the hot season almost dries up . There is a good deal of cultivation along the river , but few villages . The Kabul - Kandahar Highway passes this way ( another reason for supposing the Tarnak to be Arachotus ) , and the people live off the road to avoid the onerous duties of hospitality . In 2008 a project was initiatated to rehabilitate the Dahla Dam , and associated irrigation system . - Ghazn or Ghaznai, also historically known as Ghaznn or Ghazna, is a city in Afghanistan with a population of nearly 150,000 people. It is located in the central-east part of the country. Situated on a plateau at 7,280 feet (2,219 m) above sea level, the city serves as the capital of Ghazni Province. It is linked by a highway with Kandahar to the southwest, Kabul to the northeast, and Gardez and Khost to the east. The foundation stone of Ghazni Airport was laid in April 2012 which now serves Ghazni and other nearby eastern Afghan provinces. - The Boghra Irrigation Canal is a man-made canal some 155 kilometres long in central Afghanistan in Helmand Province, serving to divert water from the Helmand River and the Arghandab for farmland. It was built in the 1950s and is controlled by the Helmand and Arghandab Valley Authority. - Girishk (also Gereshk) is a town in Nahri Saraj District in Helmand province on the Helmand River in Afghanistan, some northwest of Kandahar, at altitude. It is the centre of a rich agricultural region with the Kajakai Dam upriver diverting water to the Boghra Irrigation Canal. Girishk was originally built around a fort on the east bank of the river but was later rebuilt on the west. During the First Anglo-Afghan War (183942), the fort was captured by the British but it was later abandoned; the same thing happened in 1879. Girishk has a population of about 48,546 and has a developed hospital and a school of engineering which was built back in 1957. What entity does 'arghandab river' has the relation 'mouth of the watercourse' with?
Answer:
helmand river