Hans Jakob Fries began to take up the study of medicine, preparing at the General Military Hospital to become a surgeon. He combined his medical studies with work in the field of botany. An immediate and more exhaustive account of Fries's travels may be found in a long, precise letter which he wrote to his parents upon the completion of his journey through Siberia and which contains only personal observations. Fries's own journey almost coincided with the second scientific expedition, undertaken by Pallas during the years 1769 to 1774. The route which Fries followed through Siberia differed to a considerable extent from the customary one. The earliest trade routes from Russia into Siberia had generally led along trails and rivers far to the north; for it was there in the forests of the north that furs, the chief objective of the traders from Pskov, Novgorod, Suzdal and Tver, were most abundantly to be found.