“No two countries have reached out to each other so eagerly and moved so swiftly to bridge the huge distance of geography and history as Saudi Arabia and China have [...] If 9/11 events forced Riyadh to explore new relationships, China?s phenomenal growth and its ever-growing appetite for energy is driving it to hunt for old and new sources of oil.” Khaleej Times
Of course, with the economic relations comes political support. China isn’t particularly concerned about those pesky little human rights issues the US has been pestering the Saudis about, like religious freedom, women’s rights, etc etc etc
The New York Times quotes Gal Luft on the issue:
“With the Chinese there are no strings attached,” said Gal Luft, co-director of the Institute for the Analysis of Global Security. “They don’t talk to you about democracy or reform. They give money, the Saudis give oil and there are no hidden agendas. The Saudis find those kinds of relationships more appealing.”
For more background, read The Sino-Saudi Connection.