Prasat Khao Phra Vihan (Preah Vihear in Cambodia) is a ruin constructed from the 9th century to 12th century. Especially the kings Suryavarman I (1002–1050) and Suryavarman II (1113–1150) made the special efforts. Now there is a territorial issue between Thai and Cambodia. The issue includes political issue. Besides, I think the issue includes the lack of understanding of histories. Both countries are on the great histories. And the histories have mutual relationship. Khmer cultures have a big influence on Thai culture. For example, King Ramkhamhaeng made the Thai alphabet consulting Khmer script. Thai influenced on Cambodia, too. And both people should respect the histories. Then the most important thing is that both countries administer this ruin together. I think so. But I know the solving this issue is very hard. Cause Japanese government has the territorial issue with China and Korean and Russia gover, too. We should think the sensitive issue like this without personal emotion and make a great effort to solve.