察尔汗: Mongolian and Tibetan transcription into Chinese
in brief, 察爾汗 is derived from mongolian.

the long explanation:

about 1763, there was a large-scale standardisation of names from mongolian, tibetan and various languages used by muslim into han chinese and manchurian. the result was the 24-volume book "欽定西域同文志" (~ made by imperial order 欽定, western region 西域, same language 同文, record 志).

the internet archive (which is blocked in "that area") has a copy:

https://archive.org/search.php?query=欽定西域同文志&amp;and[]=subject%3A%22四庫全書薈要%22

volume 1 has the rationale, guidelines (p1-p42) and table of contents (p43-p57), volume 14-17 are kokonur related

https://archive.org/details/06078133.cn

my interpretation is, the mongolian character "цагаан" "tsagaan" ("white" colour) is transliterated to "察罕" (older version) or 察爾汗 (modern version) in chinese and "qarhan" in english.

in the above mentioned book, volume 14, there're several places starting with "察罕"

"察罕鄂博" https://archive.org/details/06078140.cn/page/n72

"察罕哈達" https://archive.org/details/06078140.cn/page/n78

"察罕托輝烏魯" https://archive.org/details/06078140.cn/page/n88

"察罕托羅海" https://archive.org/details/06078140.cn/page/n106




all of them mentioned "蒙古語察罕白色" (~in mongolian, "qarhan" means white colour). most likely, "qarhan" / "tsagaan" (察罕) referred to the color of salt, not the salt itself.

further description of playa, or salt lake are modern suffix.

have fun :)