Restive Xinjiang, strategically located on the borders of Central Asia, Pakistan, India and Afghanistan, is a key part of what Beijing officially refers to as its "one belt, one road" strategy to develop trade and transport links across Asia and beyond.
Visiting Kazakh capital Astana and commercial hub Almaty from May 1-4, Xinjiang's party chief and top official, Zhang Chunxian, said Xinjiang and Kazakhstan would both benefit from the new Silk Road, the official Xinjiang Daily said.
China was keen to get more Xinjiang companies to invest in Kazakhstan and was pleased with the warm reception the ones already in Kazakhstan had received, Zhang was quoted as saying.
He also visited the company which oversees the pumping of Central Asian gas into Xinjiang via Kazakhstan, the paper added.
Zhang then oversaw the signing of five energy, agriculture and industrial projects worth more than $2 billion, the report said.
China wants to see prosperity and stability in Central Asia as it tries to tackle unrest in Xinjiang, home to the Muslim Uighur people who speak a Turkic language, many of whom chafe at Chinese restrictions on their religion and culture.
Hundreds have died in unrest in recent years, blamed by China on Islamist militants with links to Central Asia and beyond.
Rights groups and exiles say China's repressive policies are more to blame for the unrest than any cohesive militant threat. China denies abusing anybody's rights in Xinjiang.
The newspaper said Zhang visited a mosque in Astana, where he got a "deep understanding of how Kazakhstan manages religious affairs".
This the second time in a month Zhang has been to one of Xinjiang's neighbours to boost commercial ties.
In April, Xinjiang companies signed deals worth about $2 billion with Pakistan as Zhang visited, seeking to cement ties with an important security partner.
China has long urged Pakistan to weed out what it says are militants from Xinjiang, who are holed up in lawless ethnic Pashtun lands on the Pakistan-Afghan border, home to a mix of groups, including the Taliban and al Qaeda.
