Kalmyk family, Qing-Dynasty China, 1906-1908

The photo was taken by Carl Gustaf Emil Mannerheim, who had a an expedition to China between 1906-1908:

When Mannerheim returned to Saint Petersburg, he was asked to undertake a journey through Turkestan to Beijing as a secret intelligence officer.

The Russian General Staff wanted accurate, on-the-ground intelligence about the reforms and activities by the Qing dynasty, as well as the military feasibility of invading Western China: a possible move in their struggle with Britain for control of inner Asia. The cover story for this intelligence-gathering operation was a scientific exploration together with the French archeologist Paul Pelliot. Disguised as an ethnographic collector, he joined Pelliot’s expedition at Samarkand in Russian Turkestan (now Uzbekistan). They started from the terminus of the Trans-Caspian Railway in Andijan in July 1906, but Mannerheim quarreled with Pelliot, so he made the greater part of the expedition on his own.

Mannerheim undertook his journey through Asia to China on horseback. The total length of the journey was 14 thousand kilometres and it took two years from 1906 to 1908. Mannerheim took his cover role seriously and collected a lot of ethnographic material from hitherto almost unexplored areas; thus the journey produced valuable geographical and ethnological research results.

https://en.wikipedia.org/wiki/Carl_Gustaf_Emil_Mannerheim#Journey_to_Asia

The description of the photo on wikimedia says this in Finnish:

kalmukkipäällikkö Nasumbatovin vaimo ja lapset Tekesin laaksossa

Translated to English with deepl:

The wife and children of Kalmyk chief Nasumbatov in the Tekes Valley

Tekes County is in Xinjiang, China, but Kalmyks live in Eastern-Europe, in Kalmykia, Russia. They may be from some other Mongolic nationality, not Kalmyk, or at the time they used Kalmyk as a general term for Mongolic peoples.