Everyone cheered the figures out of China last week, with much of the glee focused on the rail freight graph moving upwards. Trouble is, those volumes are still way below those for 2010-11.

And those old cliches mean something, as in “one swallow doesn’t make a summer”.

The great activity numbers were driven by investment spending and there has also been rapid credit growth in China earlier in the year. Of course, the economic activity is going to spike if there is central government stimulus (although Beijing was never rash enough to mail $A900 cheques to every low-income taxpayer).

But as one close observer of the China economy emailed to me overnight, “this could actually increase the chances of a sharper slowdown in the next 12 months, as the authorities step up their efforts to rebalance the economy … This leaves plenty of scope for negative surprises from China’s commodity demand and for fresh falls in prices“

There is no question, of course, that China is an important influence on our economy — and on the success or otherwise of Australia’s mining sector.

Last year, Australia sold $38.7 billion worth of iron ore to China, along with $5.42 billion of coal and $5.53 billion worth of gold.

But let’s leave China to one side for the moment. It is quite extraordinary how the business media has focused so much on China, but not our other vital customers in the region.

According to Department of Foreign Affairs and Trade, Japan last year bought $14.94 billion worth of our coal, $9.04 billion of iron ore, and $1.5 billion of our copper ores and concentrates. We are No.3 on Japan’s list of import sources.

South Korea took $4.53 billion worth of Australia’s iron ore and $5.42 billion of coal that same year. Taiwan is a smaller customer, but you can’t sneeze at earning $2.9 billion from coal sales and $1.45 billion from iron ore shipments.

While the jury is still out on whether China is going to hit more bumps on its economic road, there is general consensus that our other big customers in Asia are facing some serious problems.

First, Japan. As one website summed up the country’s debt problem: “One quadrillion. That's one thousand trillions. One million billions. One billion millions. It's also, as of June 30, the size of Japan's total outstanding debt in yen“.

If you want it presented numerically, that’s 1,000,000,000,000,000 yen. In our money, that’s $11.47 trillion (yes, “t” for trillion). The prospect of paying that down would certainly make Joe Hockey’s eyes water.

The Japanese are going down the inflation path as the only option to cope with that debt. It plans to pluck 60 trillion yen worth of new government bonds from thin air. It won’t end well.

But there are other worrying signs. This week the Nikkei news service reports that trade between China and Japan fell 10.8% in the first six months of 2013.

In fact, Japan did the better: its imports from China dropped 6.1%, but Chinese purchases from Japan were down an astonishing 16.7% – with the biggest decreases in metal processing machinery, construction and mining equipment (along with semiconductors).

Then we had the GDP figures out of Japan. Gross domestic product grew 0.6% in the April-June period, indicating an annualised increase of 2.6%, down from the 4.1% annual rate in the first three months of the year. Analysts were expecting growth in the June quarter of 3.6%.

Here’s another straw in the wind. Investment by the Japanese private sector was down in the June quarter, the GDP’s bacon being saved only by exports and — significantly — public spending.

In that same June quarter, South Korea’s GDP rose just 1.1%. You may be staggered to learn that this was higher than most analysts expected.

The growth was attributed to Chinese demand, and robust sales of smartphones (thank you, Samsung) and property. Interesting, government consumption rose 2.3%.

The big worry in Seoul now is China. It takes 25% of South Korean exports, and exports comprise 50% of South Korea's GDP.

The story is pretty much the same in Taiwan.

Should China suddenly surge, the worst-case scenario for us and the other economies of East Asia will be averted.

If not, or if China hits another bump, then the reverberations will begin in its big trading partners in the region — and then spread inexorably to Australia and our miners.