The area is in the lands of the Gandangara people and the Tharawal people. The first European settlement was named Hoare Town. The area is named thus on a map made by Surveyor General Sir Thomas Mitchell, in 1865. The two largest land grants in the district were those of Dr Henry Grattan Douglass and Jean Baptiste de Arrietta. Douglass in time gave his name to the town, the final "s" of his name being lost due to a cartographer's error; de Arrietta is remembered by the locality "Spaniard's Hill", lying to the north of the town.