"South Korean exports, in particular, are a good proxy for how China is performing given the high amount of intermediate goods that Seoul exports to Beijing," Evans-Pritchard said.
China buys around one-fourth of South Korea's exports and data on Wednesday revealed South Korea's total May exports contracted 6 percent on-year, marking nearly one year of straight declines and a major miss on the 1.6 percent expansion Reuters had anticipated. Exports to the world's second-largest economy meanwhile fell 9.1 percent on year, down for the 11th consecutive month.
This indicates Chinese import demand is weakening on the back of tepid appetite from mainland consumers and enterprises, Evans-Pritchard said.
Japanese exports paint an equally glum picture. April data showed a 10.1 percent annual fall, the fastest decline in three months, with exports to China falling 7.6 percent. China's share of Japan's exports amounts to 17.5 percent.
Taiwan, which counts China as its biggest export market, witnessed an 11.4 percent annual plunge in April exports, with orders to China tanking 10.9 percent.
It's not just Asian trade data that suggest a slowing China, manufacturing Purchasing Manager's Index (PMI) are also helpful, Evans-Pritchard added.
"These PMIs correlate with Chinese export performance simply because when Asian factories get more new orders, that likely signals an increase in Chinese intermediary goods."
But regional factory activity declined in May. Japan's PMI stood at 47.7, its fastest pace of decline in over three years, South Korean factories reported a reading of 50.1. in May, little changed from the previous month, and Taiwan's PMI declined to 48.5, its fastest fall since October.
Despite the general weak trend, there is one bright indicator from Asia that reflects well on China, according to Iris Pang, Natixis' senior economist.
"The increasing wealth levels of Asian consumers, especially in Vietnam and the Philippines, might have a positive impact on China."
Domestic consumption in Southeast Asian emerging markets is robust, and because the services sector in these countries still require a certain amount of manufactured goods to operate, that demand could be a boon for China, she explained.
While Asian data do offer insights on the world's second-largest economy, both Pang and Evans-Pritchard believe the best external indicators come from the U.S. and euro zone. China's share of U.S. imports stood at 21.5 percent in 2015, while its portion of European Union imports amounted to 20.3 percent, according to official data.
But recent reports point to the same conclusions as those of Asia. U.S. exports slipped 0.9 percent in March, while European exports edged 1.3 percent lower between February and March.□
Nyshka Chandran , CNBC