The province of Khuzestan can be basically divided into two regions; the rolling hills and mountainous regions north of the Ahvaz Ridge, and the plains and marsh lands to its south. The area is irrigated by the "Karoun", "Karkheh", "Jarahi" and "Maroun" rivers. The northern section maintains a non-Persian Bakhtiari minority, while the southern section always had diverse minority groups known as Khuzis. Since the 1940s, a flood of job seekers from all over Iran to the oil and commerce centers on the Persian Gulf Coast has made the region more Persian-speaking. Presently, Khuzestan still maintains its diverse group, but does have Arabs, Persians, Bakhtiari and ethnic Qashqais and Lors.