While the personal experiences of non-natives who visited the Indigenous people of what is now called Alaska formed the basis of early research, by the mid-20th century archaeological excavations in southwestern Alaska allowed scholars to study the effects of foreign trade goods on 19th-century Eskimo material culture. Also, translations of pertinent journals and documents from Russian explorers and the Russian-American Company added breadth to the primary source base. The first ethnographic information about the Yup'ik of the Yukon-Kuskokwim Delta was recorded by the Russian explorer Lieutenant Lavrenty Zagoskin, during his explorations for the Russian-American Company in 1842–1844.