China bears beware: Dennis Gartman of "The Gartman Letter" said Monday that a more rapid pace of manufacturing in China in May suggests that those with a bearish view on the world's second-largest economy will end up on the wrong side of history.

On CNBC's "Fast Money," Gartman said that China's economy is doing better and will continue to strengthen.

"On balance, China is moving from the lower left to the upper right on the charts," Gartman said. "The economy is moving stronger. So if that makes me a China bull, I've been one for a long time—I will continue to be one."

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The latest Purchasing Managers' Index data for May showed that China had the strongest expansion of factory activity in five months.

Despite stronger data, Gartman said there are still a fair number of China skeptics.

"Very smart people have been calling about the demise of China for the past two and a half decades," he said. "They have been consistently and completely wrong."

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