Complex sentence: After spending one and a half years in Kalimpong he settled in Rumtek Monastery (Sikkim), the main seat of the 16th Karmapa whom he served for 17 years, the last 9 years of which he acted as Dorje Lopön (Vajra Master).
Split into simpler sentences: After spending one and a half years in Kalimpong he settled in Rumtek Monastery (Sikkim), the main seat of the 16th Karmapa. There he served him for 17 years, the last 9 years of which he acted as Dorje Lopön (Vajra Master).