Complex sentence: The Red River Colony (or Selkirk Settlement) was a colonization project set up in 1811 by Thomas Douglas, 5th Earl of Selkirk, on of land granted to him by the Hudson's Bay Company, under what is referred to as the Selkirk Concession.
Split into simpler sentences: The Red River Colony (or Selkirk Settlement) was a colonization project set up in 1811 by Thomas Douglas, 5th Earl of Selkirk on of land. This land was granted to him by the Hudson's Bay Company, which is referred to as the Selkirk Concession.