President Xi Jinping said China respected the independence and integrity of Mongolia as he wrapped up a two-day trip to the resource-rich but sometimes suspicious neighbour.
Xi spoke to the Mongolian parliament yesterday after the two nations had signed a series of trade deals and promised to upgrade their bilateral relationship to a comprehensive strategic partnership.
"China respects Mongolian independence and integrity," Xi said. "Both nations should give mutual firm support to each other in core issues concerning sovereignty, security and territorial integrity,
"China is willing to offer opportunities to Mongolia and other neighbours for common development. You can take a ride on our express train or just hitchhike. All are welcome."
Xi is the first Chinese president to speak at the State Great Hural of Mongolia. When his predecessor, Hu Jintao , visited in 2003, he said both nations needed to build trust.
A joint declaration on Thursday pledged that neither side would take action that would damage the other's sovereignty. The two also committed to almost double bilateral trade to US$10 billion by 2020, and to deepen business ties.
One of the deals concerns financing for a railway to transport coal. China has also agreed to allow Mongolia to use its northern seaports.
China currently buys almost 90 per cent of Mongolia's exports. Trade between them reached US$6 billion last month, making up almost half of Mongolia's total foreign trade.
Relations between the two countries have not always been cordial, and Mongolia remains wary of China's expansion and its growing influence.
The 19th-century domination by Beijing that ended with the integration of Inner Mongolia into China is a bitter memory. Then in 2006, Beijing's former ambassador Gao Shumao was dubbed a "most unwelcome foreigner" by the Mongolian media after he said both Chinese and Mongolians were descendants of Genghis Khan.
Since then, economic ties have grown. Xi said China would take care of the interests of its neighbours, and stick to the path of peaceful development.