Many factors are going around for the cause of the Emerging Market selloff. Trade wars, high debt loads, or trade deficits. These factors are always a tinderbox for a financial or economic crisis but not the spark. In this case the main factor of the strain is not a tweet or a 'sudden' realization of poor economic fundamentals. It was the steady and consistent rise in the Dollar.
The rise in the Dollar starting in late 2014 has put a strain on emerging markets but interest rates in the US were still very low compared to local currencies. in 2017 we saw rates on the 2 year and other shorter dated securities start to rise as rate expectations took hold in the markets. It wasn't until Sept. of 2017 that markets started to believe in the FEDs message and rates went up aggressively on the short end of the curve. This is where the real pain came in for EM as higher rates and a stronger Dollar made it very difficult to get out of debt obligations as well as finance the existing ones.
With the Jackson Hole meeting coming up at the end of this week we may see another turning point this September as well. One where the Fed talks back some of the recent hawkishness in light of the global signs of a slowdown or the more likely scenario. The data in the US shows there to be more need for rate increases to keep inflation at bay. There is little evidence in the US that higher rates are affecting the economy so there is no reason for the FOMC to worry, and it would be prudent to have higher rates in the future so the US can better stimulate the economy if the slowdown does occur. This message does not bode well for Emerging markets. But in this lies opportunity, with the US market hitting a record high again today, it might be a good time to pull some money off to the sidelines and await a good buying opportunity in EM. After all you are getting a higher yield while you wait.