Complex sentence: Sitka served as the capital of the Department of Alaska (1884-1902) and District of Alaska (1902-1906), when the seat of government was relocated north to Juneau in 1906.
Split into simpler sentences: Sitka served as the capital of the Department of Alaska (1884-1902) and District of Alaska (1902-1906). The seat of government was relocated north to Juneau in 1906.