In 2011, the Institute of Archaeology of the Uzbekistan Academy of Social Sciences and the Institute of Archaeology with the CASS signed a deal to jointly excavate the site.
The work started the following fall, but the Chinese team did not rush to dig.
The team, headed by Zhu Yanshi, a specialist in the archaeology of ancient capitals, spent three years drawing a digital map of the site, with the help of drones, and using technology of precision measurement and computer mapping.
In 2015, Zhu invited his old partner Wang Cunjin, who is skilled in using the traditional Luoyang shovel, to the site.
A U-shaped cylinder four to six centimeters in diameter, the Luoyang shovel is widely used in Chinese field archaeology. It lets the user extract a section of earth while preserving the soil structure.
Researchers can analyze the color, texture and intensity of soil for any evidence of underground structures, to find if it is soil from a road, a tomb or a city wall. Usually, the soil of a city wall is hard and firm.
At the Mingtepa site, archaeologists started to look for the outer walls of the city, but with no signs on the surface. It was like trying to find a needle in a haystack.
The Chinese team recruited 12 Uzbek farmers, and Wang taught them how to use the shovel.
Every day the farmers dug small holes, and Wang examined the extracted soil from each hole.
Another colleague put the position information of the holes and soil information into the digital map previously drawn. The position data was collected using the Real Time Kinematic technique, which provides centimeter-level accuracy and is more precise than GPS.
Wang found the texture of the soil was quite different from that in China.
"Some soil is very soft. In China, you would not think it is soil on the city wall. But here as we made more comparisons between different soil samples, we found some soft soil was a bit unusual and it might be what we were looking for," Wang said.
Every evening, Wang and his colleagues compared soil samples from different holes and discussed possible locations of the city walls.
A breakthrough was made in the fall of 2016. Signs indicated that there might be a city wall in the eastern part of the ruins.
Zhu decided to dig a small pit in the area - and they found the outer walls.
"Once we made the breakthrough, it became easier to trace the wall," Zhu said.
The outcome amazed the Uzbekistan team.
"You are not only a technician. You are a real expert," Bokijon Matbabaev, leader of the Uzbekistan team, told Wang.
Following excavations found outer walls of the city in the other three directions. It broadened the site size from 500 by 800 meters to 2,100 by 1,300 meters, meaning that about 2,000 years ago it was the largest city in the Fergana Valley.
The team also unearthed a craft workshop and a graveyard. There have been guesses that Mingtepa was simply a temporary garrison fort for nomads. The workshop and graveyard came as proof that Mingtepa was an ancient settlement.
"With such a large area and the structure of both the inner city and external city, Mingtepa must have been an important city in the Dayuan state around 2,000 years ago," Zhu said.
"The outcomes of the excavations in the past five years were more than we achieved in recent decades," Matbabaev said.
"China' s cultural heritage is rich, so Chinese archaeologists have accumulated great expertise and experience in field archaeology," said Wang Wei, then director of the CASS Institute of Archaeology.
