Khmer people are very poors from 14 century to 20 century and have no knowledges because Khmer people never change their behavior,they keep repeated doing same things over and over again, Khmer people just do farming and create fishes and insects to eat and sell fruits and vegetables,the way they think still the same like ancient times.There is no scientists, biologist, chemists, researcher, engineering, physicist, astronomer, entrepreneur. Look at Japan,they think different from us,they have scientists, biologist,chemists,researcher, engineering, physicist ,astronomer anthropologist, geologist, technology ,entrepreneur.They exports thousands of products every year to other countries,they don't rely on farming and fishing and catching insects,they use their brains to have ideas to create merchandise to sells, Khmer people must learn from Japan.