A total of five boundary stones were erected on the Sino-Russian border in Hunchun, Northeast China's Jilin Province on Wednesday, marking a territory returned to China two decades ago, which experts believe has resulted from booming Sino-Russian relations.

Local officials have attended a ceremony to erect the boundary stones and discuss building a port, the China News Service (CNS) reported Wednesday.

Russia returned 4.7 square kilometers of territory to Hunchun in 1993, when China and Russia restarted the border demarcation process. In 2014, China's State Council approved five names for places in the returned territory, a local official surnamed Wang told the Global Times on Thursday.

"The erection of the boundary stones shows that the mutual trust and cooperation between the two countries have improved significantly," Gao Fei, a professor of Russian studies at the China Foreign Affairs University, told the Global Times.

According to Gao, boundary issues have always been a sensitive topic for the Russian government and its people. China did not immediately erect the stones after they determined the boundary, since China downplayed the return of territory out of political concerns. 

"The Russian society was upset about giving the territory back to China after the demarcation. Due to the special strategic position of the Russian Far East, at that time Russians used to be worried that Chinese might take more territory from us in the region," a professor at Russia's Ivanovo State University who asked for anonymity told the Global Times on Thursday.

She said that with cooperation and communication deepening between the two countries, Russians now hold a relatively friendly attitude toward China.

China has gone ahead with the erection of the markers because the ties have achieved a new level, Gao said.

The two countries have vowed in May to work together to deepen their comprehensive strategic partnership, the Xin-

hua News Agency reported.

Gao added that solving boundary disputes is vital to economic and cultural cooperation between China and Russia, adding that the erection of the boundary stones represents a good start for the development of the region.

The returned land is only 60 kilometers away from Ussuriysk, the biggest market that sells Chinese commodities in the Russian Far East, CNS reported.

"Such geographical advantages will promote commercial exchanges between the area and Russia," Gao pointed out.

With a shared boundary of more than 4,300 kilometers, as determined by a survey conducted in July 2008, the Sino-Russian border issue has come to an end. "The boundary disputes have bothered Russia and China for more than 300 years. They have been solved within decades, mainly because Sino-Russian relations have improved significantly," Gao added.