When Alaska was first purchased, most of its land remained unexplored. In 1865, Western Union laid a telegraph line across Alaska to the Bering Strait where it would connect, under water, with an Asian line. It also conducted the first scientific studies of the region and produced the first map of the entire Yukon River. The Alaska Commercial Company and the military also contributed to the growing exploration of Alaska in the last decades of the 19th century, building trading posts along the Interior's many rivers.