Southwest China’s Tibet Autonomous Region has banned visitors from passing through a state nature reserve to access other areas, as an environmental protection measure.

In a circular released Friday, the regional forestry bureau said that any crossing at the Changtang National Nature Reserve (CNNR) will be illegal. It specifically mentions that people should not pass through the CNNR to reach two other state nature reserves, one in Xinjiang and another in Qinghai.

The CNNR covers six counties in Tibet’s Nagqu Prefecture. With an area of 298,000 square km and an average altitude of 5,000 meters, it is China’s biggest and highest reserve. The area is a wildlife paradise, and home to a variety of wildlife species and numerous lakes.

The circular called on tourists, adventure enthusiasts and tourism agencies to comply with the reserve’s laws and regulations to “protect the last pure land on earth.”

Tibet has increased protection efforts at the CNNR. In 2015, the regional government established 73 management stations at the reserve and hired a total of 780 farmers and herdsmen to patrol, manage and protect the reserve at a cost of 300 million yuan (43 million dollars).

Police in southwest China’s Yunnan Province have busted a drug-trafficking case, with three suspects detained, authorities said Saturday.

More than 57 kg of methamphetamine and two vehicles were confiscated in a raid on Tuesday, according to the public security bureau of Zhenyuan County.

On Tuesday, police intercepted an SUV on a local highway in Zhenyuan and detained a suspect surnamed Xie. Later, another SUV carrying another two suspects was stopped.

Further investigation is under way.

The ruins of an ancient city have been discovered in southwest China.

Archaeologists have found the remains of several walls in Yunnan’s Midu County, believed to be part of Baiya City, and dating back to the early years of the Tang Dynasty (618-907) more than 1,000 years ago.

Accounts of the old town of Baiya City first appear in a history book written by military official Fan Chuo during the Tang Dynasty. Fan said that Baiya City had an old town and a new town, which were closely connected. A previously discovered “old town” was about two kilometers from the confirmed new town, contradictory to the book, according to historian and archeologist He Jinlong.

“From the location of these newly discovered ruins, much closer to the new town, we are pretty confident that it is the authentic old town,” He said. “As excavation continues, we will know more details.”

Domestic and foreign records about Baiya City are quite limited, and the new discovery will provide valuable evidence for research into the ancient civilization of west Yunnan, He added.

A large group of milu Deer have been spotted in central China’s Hunan Province, authorities said.

Staff with Hunan Provincial Forestry Department found 62 wild milu deer during a drone inspection in a state nature reserve near Dongting Lake, the second-largest freshwater lake in China. It is the biggest group of wild milu deer ever seen in the area.

Staff with the department found the deer foraging during a survey on Thursday.

Last year, authorities found 41 of the deer in the reserve.

“The extra deer spotted this year must be the calves,” said Zhang Hong, an official with the administration of the nature reserve.

Milu, also known as Pere David’s deer, is a species endemic to China, but overhunting and loss of habitat led to its near extinction in the early 20th Century.

In 1986, the British government gifted 39 milu deer to Dafeng Milu National Nature Reserve in east China’s Jiangsu Province, starting a revival of the population in its homeland.

There are a total of 18 professional think tanks under the Chinese Academy of Social Sciences (CASS), president of the academy Wang Weiguang has said.

Wang made the remarks at an international forum on Chinese philosophy and social sciences held in Beijing Friday, saying that the academy is dedicated to fostering national high-end think tanks with extensive influence both at home and abroad.

The tanks primarily focus on Marxism, economics and finance, social culture, international relations and border areas, according to the academy.

As this year marks its 40th anniversary, Wang said the academy has become a prestigious institute in the study of philosophy and social sciences in China.

By the end of 2016, the academy has completed almost 13,000 monographs, over 147,000 papers and more than 27,000 research reports, Wang said.

The CASS also has over 160 cooperation agreements with academies, think tanks, international organizations or higher education institutes in more than 100 countries or regions.