Aerial photo shows sheep grazing in corn field in Minghua Township of Sunan Yugur Autonomous County, northwest China's Gansu Province, Oct. 15, 2020. From mid-October to next mid-March every year, over 300 herdsmen in about 50 villages in Sunan Yugur Autonomous County drive more than 100,000 cattle and sheep to lower elevation corn fields, dozens of kilometers away, in a bid to preserve the pasture for livestock grazing in summer and autumn. (Xinhua/Fan Peishen)

Photo shows the migration of sheep in Sunan Yugur Autonomous County, northwest China's Gansu Province, Oct. 15, 2020. From mid-October to next mid-March every year, over 300 herdsmen in about 50 villages in Sunan Yugur Autonomous County drive more than 100,000 cattle and sheep to lower elevation corn fields, dozens of kilometers away, in a bid to preserve the pasture for livestock grazing in summer and autumn. (Xinhua/Fan Peishen)

Aerial photo shows the migration of sheep in Sunan Yugur Autonomous County, northwest China's Gansu Province, Oct. 15, 2020. From mid-October to next mid-March every year, over 300 herdsmen in about 50 villages in Sunan Yugur Autonomous County drive more than 100,000 cattle and sheep to lower elevation corn fields, dozens of kilometers away, in a bid to preserve the pasture for livestock grazing in summer and autumn. (Xinhua/Fan Peishen)

Aerial photo shows the migration of sheep in Sunan Yugur Autonomous County, northwest China's Gansu Province, Oct. 15, 2020. From mid-October to next mid-March every year, over 300 herdsmen in about 50 villages in Sunan Yugur Autonomous County drive more than 100,000 cattle and sheep to lower elevation corn fields, dozens of kilometers away, in a bid to preserve the pasture for livestock grazing in summer and autumn. (Xinhua/Fan Peishen)