Uber is the world’s most valuable startup—now valued at close to $51 billion, according to the Wall Street Journal—and the undisputed king of the ride-hailing industry. At least at the moment. But outside the US, where Uber is most aggressively seeking growth, its overseas rivals are increasingly banding together in a bid to hamper its rapid expansion.

On Monday, Reuters reported that Chinese ride-hailing giant Didi Kuaidi had invested in Ola, the biggest ride-summoning app in India. The amount was not disclosed, though the Times of India, citing unnamed sources, previously reported that Didi Kuaidi’s stake in the company would be around $30 million. Ola confirmed the investment to WIRED but not the amount. Didi Kuaidi did not immediately respond to a request for comment.

Didi Kuaidi’s investment comes right on the heels of the announcement of its partnership with US-based Lyft. Earlier in the month in New York, the two companies revealed they would link their apps. Lyft users traveling in China could hail Didi Kuaidi drivers from their Lyft app, and vice versa. The feature is set to go live by early 2017. But the partnership appears to go beyond apps. Didi Kuaidi also reportedly invested $100 million in Lyft earlier this year. It has also invested in the Singapore-based ride-hailing company GrabTaxi.

All of this cooperation among Uber's rivals signals the emergence of consolidation as the key strategy for challenging the global juggernaut that is Uber. As Uber’s most formidable competitor in China—the company's most coveted market—Didi Kuaidi is in a prime position to lead this charge, and it’s not shying away from the task. Consolidation is also in the interest of Uber rivals' deep-pocketed investors. Chinese tech giants Alibaba and Tencent, for instance, have a stake in Didi Kuaidi and Lyft, and Japan-based SoftBank has investments in Ola and Didi Kuaidi.

Uber has made no secret of wanting to own the Chinese market, recently raising $1.2 billion in fresh funding to pour into its China operations. It has also expressed a special interest in India, now the world’s fastest growing major economy. But its rivals are determined to create at least a few bumps along Uber’s road to global dominance.