In Hong Kong, Tencent’s market capitalization rose above $400 billion in early trading on Thursday before closing just below that threshold at $396 billion. Alibaba closed in New York trading on Thursday with a market value of $415 billion. The two companies still lag Amazon and Facebook, which are valued at more than $450 billion, and are significantly smaller than Apple, the world’s most valuable public company with a market capitalization exceeding $800 billion.

In Silicon Valley, some tech companies have begun taking cues from their Chinese rivals. Tencent’s WeChat offered speedier in-app articles before Facebook, created a walkie-talkie function before WhatsApp, and made use of QR codes as a way to connect on a social network long before Snapchat.

Both Alibaba and Tencent have long been successful in China, but recent events have given them an added push. In China, people often talk about three internet companies that dominate the technology world: Alibaba, Tencent and a search company called Baidu, which is sometimes called the Google of China.

But Baidu has stumbled as Chinese users skipped personal computers entirely and turned to smartphones, and it has had trouble competing in a financial arms race between Tencent and Alibaba. The two companies have been plowing money into new businesses like food delivery and online video.

Alibaba and Tencent owe part of their success to China’s censorship and suspicion of foreign tech firms, which have kept American giants like Facebook and Amazon out of their orbit. But the two have also scored some major technology innovations in their own right. They dominate a smartphone culture that in many ways is superior to that of the United States. Chinese people use their dueling mobile payment systems to settle their restaurant tabs, to shop online, to pay their utility bills, to rent bicycles and even to put money into investments.

Despite their size, Alibaba and Tencent are mostly anchored in China, though both are pushing to expand. Most of Alibaba’s earnings come from its ad and commissions business in China. The company had just under $400 million in revenue from international commerce. While Tencent has games like League of Legends that are played across the world, the bulk of its revenue comes from games and ads in China.

Both have made use of investments and acquisitions to enter into new markets in recent years — with uneven results. Alibaba has invested in a payments company in India, and it bought into three different e-commerce companies in Southeast Asia. With Amazon also readying its own Southeast Asian campaign, the hugely populated region of disparate cultures could be the first place the two e-commerce Goliaths compete face-to-face on neutral ground.