Question: When did the stronghold of the Boyd Family begin to be built?

Context paragraphs:
Sir Thomas Boyd: Sir Thomas Boyd of Kilmarnock was a 14th-century Scottish landowner and lord of Kilmarnock in Ayrshire.  He was the son of Sir Robert Boyd, who fought at the Battle of Bannockburn.  In 1346, he was taken prisoner at the battle of Neville's Cross.  He is known for building the earliest parts of Dean Castle in around 1350, and the castle still stands today and is open to the public.  Sir Thomas was succeeded by his son, Thomas (died 1432).  Sir Thomas' later descendants were the Earls of Kilmarnock.

Martin Boyd: Martin à Beckett Boyd (10 June 1893 – 3 June 1972) was an Australian writer born into the à Beckett–Boyd family, a family synonymous with the establishment, the judiciary, publishing and literature, and the visual arts since the early 19th century in Australia.

Boyd's Windmill: Boyd's Windmill, also known as Boyd's Wind Grist Mill, is a historic smock mill at Paradise Valley Park on Prospect Avenue in Middletown, Rhode Island.  John Peterson built the windmill on Old Mill Lane in Portsmouth, Rhode Island in 1810, and William Boyd purchased it in 1815.  It originally had four common sails, but four more were added by the family.  The mill is a timber-frame structure, octagonal in shape, and about 30 ft tall, with a rotating cap powered by eight vanes with canvas sheets.  The grindstones in the middle of the mill are Fall River granite; the upper one, which is connected to the power mechanisms, rotates six times for each turn of the mill's main shaft.  In 1916 Benjamin Boyd removed the original vanes and powered the mill using a gasoline engine.  It is one of only two windmills (out of what was estimated to be more than thirty) to survive on Aquidneck Island.

Battle of Muhu: In January 1227, when the sea had frozen hard, a large Crusader army after the call of the Papal legate William of Modena was gathered.  According to the Chronicle of Livonia, 20 000 troops had set out to Muhu from the estuary of Pärnu River and moved along the ice.  Since the ice was said to have been very slippery, they reached the stronghold of Muhu on the ninth day.  After seeing such a large force, the people of Muhu offered truce and allowed themselves to be baptised.  Most of the Germans didn't accept it and so they started besieging the stronghold.  The first rush was fend off with rocks and spears.  The besiegers threw rocks into the stronghold with bricoles, built a turret and undermined the wall.

Dean Castle: Dean Castle is situated in the Dean Castle Country Park in Kilmarnock, East Ayrshire, Scotland.  It was the stronghold for the Boyd Family, who were lords of Kilmarnock for over 400 years.

Arthur Merric Boyd: Arthur Merric Boyd (19 March 1862 – 30 July 1940) was an Australian painter.  He and his wife Emma Minnie (née à Beckett) established a lifestyle of being artists which many generations followed to create the popular image of the Boyd family.

Boyd family: The Boyd family is an Australian family whose members over several generations succeeded in distinguished effort in their contribution to the arts in the fields of painting, sculpture, pottery, ceramics, literature, architecture, poetry and music.  By the advent of the twenty-first century the Boyd family had reached a popular conception of identity as an artistic dynasty.  This line of artists may be said to find its nascence in the 14 January 1886 marriage of Emma Minnie à Beckett and Arthur Merric Boyd.

Loch of Trabboch: The Loch of Trabboch or Dalrympleston Loch (NS440211) was situated in a low-lying area below the old Castle of Trabboch, once held by the Boyd family in the Parish of Stair, East Ayrshire, Scotland.

While the Children Sleep: While the Children Sleep (also known as The Sitter) is a 2007 made-for-television horror film released on the Lifetime Movie Network.  The film is about a couple who hires a live-in nanny (Mariana Klaveno) who inserts herself increasingly into the family routine.  Then friends of the family begin to have mysterious accidents, as the nanny conspires to replace the mother through murder.  The film's plot was compared by reviewers to the 1992 film "The Hand That Rocks the Cradle" and the 2001 film "The Glass House", as well as others.

Brenda Niall: Dr Brenda Niall AO (born 25 November 1930) is an Australian biographer, literary critic and journalist.  She is particularly noted for her work on Australia's well-known Boyd family of artists and writers.  She was educated at the Genazzano FCJ College, in Kew, Victoria, and the University of Melbourne.

Supporting paragraphs: Sir Thomas Boyd Dean Castle
Answer: around 1350