Complex sentence: In 1811, Huron County encompassed the entire Firelands (and also included a portion of later Lorain County); and until 1837, all of the "Fire Lands" would lie within--and therefore co-exist with --'Huron County'.
Split into simpler sentences: In 1811, Huron County encompassed the entire Firelands (and also included a portion of later Lorain County). Until 1837, all of the "Fire Lands" would lie within--and therefore co-exist with --'Huron County'.