Historically, most tombs known to have grave goods in them were robbed soon after the dead person was laid to rest. So why has the tomb that your group of adventurers broken into not already suffered this fate?
Khor are a monsterous and violent race. Within five years of being born, they grow to about half human size and are very, very inteligent. As they get older, they get larger... unfortunately they become less intelligent. After their adolecesence (about seven years), they grow to human size and are of a low human intelligence. As they age, they grow larger, slower, and stupider. Most of them end their lives 3 to 4 meters in height. Khor have been reported upto 10 meters tall, though those elder giant Khor do little but hit anything that disturbs them.
As they age they get larger, they don't seem to ever die of natural causes.