1980 cover from remote Western Tibet and other mysteries

1980 cover from Purang, Tibet via Shiquanhe, Tibet to Shenyang

A beautiful usage of a classic modern stamp on an Illustrated envelope with two parrots on a perch, addressed to postcode 110024 (a district in the city of Shenyang, in Liaoning), from postcode 859500 of Bangre, 邦热 in Burang County, Ngari Prefecture, Tibet.

Franked with 4f Peonies, a painting by Qi Baishi, stamp 16-1 from the sought after set T44, cancelled by Chinese/Tibetan bilingual cancel of Burang Town (Purang, Pǔlán, 普兰, སྤུ་ཧྲེང་རྫོང་), Burang County, Ngari Prefecture, Tibet, dated 2nd July 1980:

I have not been able to locate Bangre on any maps, although the postcode.info web site places it near the southern coast of Lake Manasarovar. Burang is the administrative centre of Ngari Prefecture. It is the last (only) town on the road to the Nepalese border. The border with India is also nearby. Burang is 79km by road from the Xinkiang-Tibet Highway.

Lake Manasarovar and Mount Kailash are important pilgrimage sites for the Buddhist, Jain, Hindu and Bon religions.

Although Burang is the administrative centre, the largest town in Ngari Prefecture is Shiquanhe, 狮泉河 / ནག་ཆུ་གྲོང་རྡལ།, in Gar County. Shiquanhe is (confusingly) often called Ngari on western maps. (Shiquanhe is also sometimes confused with the nearby village of Gar or Gartok, which used to have an important market). It is 348 km by road from Burang to Shiquanhe.

Remarkably this cover had another 4f stamp, this time from the R18 definitive set, added on the back and cancelled 6 days later at Shiquanhe.

Possibly the 4f stamp was put on the back in Purang, but missed being cancelled there and was cancelled later in Shiquanhe?

Another possibility is that the sender addressed it (in the blue pen) to someone in Shiquanhe, who then wrote the Shenyang address in black ink and added the 4f stamp? The rate for local mail was 4f but long distance was 8f, so the first 4f stamp could have covered the local part of the journey?

Did all mail from Purang go to the main town of the prefecture, Shiquanhe, to be distributed from there?

Reverse with transit Tibetan / Chinese cancel of Shiguanhe tying the 4f R18 definitive & branch 24 receiver.

The receiver cancel is rather unclear, but has at the base 24 (支 = branch) which is probably:

Gongrencun Post Branch Bureau, South 11th West Road, Tiexi, Shenyang, Liaoning, China, 110024.

Or possibly:

Zangong Street Post Office, Zangong Street, Tiexi, Shenyang, Liaoning, China, 110024.

The magenta handstamp "35" is probably a postman's chop.