The image contains a legend or key explaining different symbols or markings used on a map, likely related to various expeditions or routes. Here is my translation of the text to English:
Key symbols:
______ Route of the main caravan under the leadership of the expedition of P.K. Kozlov.
======= Routes of Captain K.V.T. Napalkov.
......... Routes of Geologist A.A. Chernov.

Route of P.K. Kozlov from Monastery Labrang through Tsaidam and Sining to Lan-Chow-Fu.

==== Combined routes of Napalkov and Chernov.
△ Astronomical observation points of the expedition.
So it seems to be differentiating the routes taken by the main expedition leader P.K. Kozlov, as well as the separate routes of Captain Napalkov, Geologist Chernov, their combined routes, and marking astronomical observation sites used during these explorations in the region.