Here's an update of the long term charts of the Thai stock market (SET).
The chart below is the SET index between 1975 and August 2011, it has continued to rise albeit at a slower pace.
However, the PER was stable around 15 as the companies earning improved. A PER of 15 is relatively high for the Thai stock market.
The price to book value of the SET index increased slightly to 2.14 (from 2) back to 2007 levels and not really historically cheap.
Finally, the average dividend yield is now 3.45%, but you can get the same amount of interest in a fixed deposit in Bangkok Bank (3.5% per year for 3 year fixed deposit).
To conclude, for those who are invested in the Thai SET is may be wise to further lighten your positions given the current market valuations.