The near 9 percent slump in Chinese stocks was their worst performance since the depths of the global financial crisis in 2007 and wiped out what was left of the 2015 gains, which in June has been more than 50 percent.
With the latest slide rooted in disappointment that Beijing did not announce expected policy support over the weekend, all index futures contracts slumped by their 10 percent daily limit, pointing to more bad days ahead.
MSCI's broadest index of Asia-Pacific shares outside Japan fell 5.1 percent to a three-year low. Tokyo's Nikkei ended down 4.6 percent and Australian and Indonesian shares hit two-year troughs.
"China could be forced to devalue the yuan even more, should its economy falter, and the equity markets are dealing with the prospect of a weaker yuan amplifying the negative impact from a sluggish Chinese economy," said Eiji Kinouchi, chief technical analyst at Daiwa Securities in Tokyo.
Just as worrying was evidence that developed markets were becoming synchronized with the troubles. London's FTSE with its large number of global miners and oil firms, was down for its 10th straight day, its worst run since 2003.
The pan-European FTSEurofirst 300 was last down 5 percent at 1,355 points, wiping around 400 billion euros ($460.16 billion) off the index and taking its losses for the month to more than 1 trillion euros.
U.S. stock futures also pointed to big losses for Wall Street's main markets, with the S&P 500, Dow Jones Industrial and Nasdaq expected to open down 3.6, 4.0 and 4.9 percent respectively.
It is likely to tip the S&P 500 and Nasdaq formally into 'correction' territory - meaning stocks, at their lows, are 10 percent off their 52-week highs.
"We are in the midst of a full-blown growth scare," strategists at JP Morgan Cazenove said in a note.
