Horpa-Lavrung
Layers:
Eastern Sino-Tibetan independent branch
Burmo-Qiangic areal influences
Similarities with rGyalrong are due to contact because of geographical proximity. Sun (2018) has observed that lexical similarity percentages between Horpa and rGyalrong are in fact quite low - only around 15%.
Horpa classification (based on Sun 2018, with some of my own revisions):
Eastern
East-central
Dandong, Bian'er
Geshenza, Dasang
Far East
Niega, Bawang
Central (sTau, rTau): Daofu
Northern
Puxi
Zongke
Erkai
Northwestern
Western (Minyag)
Youlaxi
Jialaxi
Bomei
Sources
Sun, Jackson T.-S. 2018. The Ancestry of Horpa: Further Morphological Evidence. Taipei: Academia Sinica.
Nagano, Yasuhiko and Marielle Prins. 2013. rGyalrongic languages database. Osaka: National Museum of Ethnology (Minpaku).