chu lgang don pa

...as stated at (source)>[1]:

"Upon returning to the realm of Shambhala, King Suchandra began teaching and transmitting the Kalachakra Root Tantra. This tantra has then been passed down successively to the present 21st Kalkin of Shambhala. King Yashas, an emanation of Manjushri then composed the Condensed Tantra of the Kalachakra while his son, Kalkin Pundarika composed the primary commentary on the Condensed Kalachakra Tantra titled, Vimalaprabha or Stainless Light. RWB