The stuff of legends, Allan (or Allen) was an adventurer and frontiersman who refused to let ethics or scruples get in his way. Born in Morristown, New Jersey in 1752, he lived with the Seneca nation of the Iroquois Confederation for a time before the Revolutionary War. He stole Sally or Kyen-da-dent, the sister of Seneca chief Captain Bull, away from her husband in about 1775. During the Revolutionary War, Allan served as sergeant and lieutenant with Butler's Rangers, but, unusually, this does not seem to have been held against him by the Americans, despite his reputation of inflicting murder and mayhem to families on both sides.

At the end of the war, he moved to the Genesee area of New York State and lived with Mary Jemison, the white woman who was kidnapped at age 15 and raised as a Seneca. Allan's charm seems to have created problems with women throughout his life. While staying with Mary Jemison, he caused a problem between another man and his native wife but, unlike Sally, this woman stayed with her husband. In 1783, he moved to the Mount Morris area where he became a trader and farmer. Meanwhile, the Iroquois and the British on the Niagara frontier were dissatisfied with the terms of peace with the Americans. They were preparing to resume the war when Allan found out about it. He obtained some wampum fraudulently and approached the nearest American post stating that he brought the wampum as a token of peace. The Americans accepted his offer of peace, and this enraged the Iroquois and British, who were obliged by the power of the wampum to accept peace. They captured him and put him on trial in Montreal, where he was acquitted of being a traitor.

In 1786, he moved to Scottsville NY and settled on Allan's Creek (now Oatka Creek). In 1789, agents from N. Gorham and O. Phelps and Co. approached him to build a gristmill and a sawmill for them in what is now Rochester NY in return for 100 acres of what is now the heart of Rochester. He sold his Scottsville farm and built the mills, but they were ultimately unsuccessful because there simply were not enough people around to keep the mills in business. He borrowed money from his former commander, Colonel John Butler, and somehow failed to repay it. While building the mills, he found time to marry Lucy Chapman, the daughter of a man on his way to Niagara. In 1792, after his venture at Rochester, he returned with Lucy to Mount Morris and there she found out that he was already married. Eventually he was to have four wives: two native and two white.

Allan did not stay long at Mount Morris because he had applied for a grant from Lt. Gov. Simcoe because of his service in Butler's Rangers during the war. He was given 2200 acres in Delaware Township on condition that he build a gristmill and a sawmill and some church buildings where Dingman's Creek joins the Thames River at what is now Delaware Village. The mills were to belong to him but the church buildings and the land they were on were the property of the Government. Between 1797 and 1807, he was building the mills. Running out of money, as he had done in Rochester, he could not borrow any more from Col. Butler, who had died in 1896, so he began to counterfeit some. He was discovered and sent to prison. After he was released, he returned to Delaware Village, where he completed the mills and buildings. During the War of 1812, he was distrusted by his neighbours, who regarded him as an American sympathizer. He died in 1813 and was buried on the north side of the Thames. Three of his children were horse thieves and one was murdered by natives while on his way to California.

Allan was no hero but he was instrumental in the founding of three communities: Rochester and Mount Morris in New York State, and Delaware Village in Ontario.