The largest ethnic group in Cambodia are the Khmers, who comprise around 90% of the total population in Cambodia, and are indigenous to the lowland Mekong subregion in which they inhabit. The Khmers historically have lived near the lower Mekong River in a contiguous diagonal arc, from where modern-day Thailand, Laos, and Cambodia meet in the northwest, all the way to the mouth of the Mekong River in southeastern Vietnam.