Nangso Damepa (nang so mda' smad pa) lived in the thirteenth century. He was a descendent of the twelfth-century Tsawarong (tsha ba rong), through whom he was therefore descended from the Pugyel (spu rygal) kings of the Tibetan Empire, via King Namde Osung (gnam lde 'od srungs, b. 842), the son of King Tri Udumtsen (ur dum btsan, r. 836-842) also known as Langdarma (glang dar ma, or), and his younger wife.
Damepa built a castle on a mountain with darkish grass (rtswa rgya bo) in Chutsen Khazhab in Upper E (e stod chu tsan kha zhabs), present day Chusum (chu gsum) county, in the Lhokha (lho kha) region. Because of its location, the castle came to be called Gyari (rgya ri). In later centuries that castle became the seat of a prominent Lhasa family, and provided them their name, Lhagyari (lha rgya ri).
He was given an official Yuan title of Nangso (nang so), testament to his status as a local ruler.
Bibliography
Bsod nams stobs rgyas. 2009. Lha rgya ri'i lo rgyus phyogs sgrig. In Bod kyi lo rgyus rig gnas dpyad gzhi'i rgyu cha bdams bsgrigs, vol. 7, pp. 278-311. Chengdu: Si khron mi rigs dpe skrun khang. TBRC W1PD96945.
Rnam rgyal rgya mtsho. 1999. Lha rgya ri'i gdung rabs. New Delhi: Paljor Publications, pp.16-21. TBRC W00KG09731.