Aerial photo taken on May 20, 2019 shows the scenery of Norbu Lingka in Lhasa, capital of southwest China's Tibet Autonomous Region. Norbu Lingka, literally "garden of treasure" in Tibetan, covers an area of 36 hectares. (Xinhua/Purbu Zhaxi)

Aerial photo taken on May 20, 2019 shows the scenery of Norbu Lingka in Lhasa, capital of southwest China's Tibet Autonomous Region. Norbu Lingka, literally "garden of treasure" in Tibetan, covers an area of 36 hectares. (Xinhua/Purbu Zhaxi)

Photo taken on May 20, 2019 shows the scenery of Norbu Lingka in Lhasa, capital of southwest China's Tibet Autonomous Region. Norbu Lingka, literally "garden of treasure" in Tibetan, covers an area of 36 hectares. (Xinhua/Purbu Zhaxi)

Photo taken on May 20, 2019 shows the scenery of Norbu Lingka in Lhasa, capital of southwest China's Tibet Autonomous Region. Norbu Lingka, literally "garden of treasure" in Tibetan, covers an area of 36 hectares. (Xinhua/Purbu Zhaxi)

Photo taken on May 20, 2019 shows the scenery of Norbu Lingka in Lhasa, capital of southwest China's Tibet Autonomous Region. Norbu Lingka, literally "garden of treasure" in Tibetan, covers an area of 36 hectares. (Xinhua/Purbu Zhaxi)

Photo taken on May 20, 2019 shows the scenery of Norbu Lingka in Lhasa, capital of southwest China's Tibet Autonomous Region. Norbu Lingka, literally "garden of treasure" in Tibetan, covers an area of 36 hectares. (Xinhua/Purbu Zhaxi)

Photo taken on May 20, 2019 shows the scenery of Norbu Lingka in Lhasa, capital of southwest China's Tibet Autonomous Region. Norbu Lingka, literally "garden of treasure" in Tibetan, covers an area of 36 hectares. (Xinhua/Purbu Zhaxi)

Photo taken on May 20, 2019 shows the scenery of Norbu Lingka in Lhasa, capital of southwest China's Tibet Autonomous Region. Norbu Lingka, literally "garden of treasure" in Tibetan, covers an area of 36 hectares. (Xinhua/Purbu Zhaxi)