to very hot, with average highs from ; however, in the northern part of the territory, the thermometer may drop below at night and it can be freezing in December and in January, although this is rare. Western Sahara contains four terrestrial ecoregions: Saharan halophytics, Mediterranean acacia-argania dry woodlands and succulent thickets, Atlantic coastal desert, and North Saharan steppe and woodlands. History Early history The earliest known inhabitants of Western Sahara were the Gaetuli. Depending on the century, Roman-era sources describe the area as inhabited by Gaetulian Autololes or the Gaetulian Daradae tribes. Berber heritage is still evident from regional and place-name toponymy, as well as from tribal names. Other early inhabitants of Western Sahara may be the Bafour and later the Serer. The Bafour were later replaced or absorbed by Berber-speaking populations, which eventually merged in turn with the migrating Beni Ḥassān Arab tribes. The arrival of Islam in the 8th century played a major role in the development of the Maghreb region. Trade developed further, and the territory may have been one of the routes for caravans, especially between Marrakesh and Tombouctou in Mali. In the 11th century, the Maqil Arabs (fewer than 200 individuals) settled in Morocco (mainly in the Draa River valley, between the Moulouya River, Tafilalt and Taourirt). Towards the end of the Almohad Caliphate, the Beni Hassan, a sub-tribe of the Maqil, were called by the local ruler of the Sous to quell a rebellion; they settled in the Sous Ksours and controlled such cities as Taroudant. During Marinid dynasty rule, the Beni Hassan rebelled but were defeated by the Sultan and escaped beyond the Saguia el-Hamra dry river. The Beni Hassan then were at constant war with the Lamtuna nomadic Berbers of the Sahara. Over roughly five centuries, through a complex process of acculturation and mixing seen elsewhere in the Maghreb and North Africa, some of the indigenous Berber tribes mixed with the Maqil Arab tribes and formed a culture unique to Morocco and Mauritania. Spanish province While initial Spanish interest in the Sahara was focused on using it as a port for the slave trade, by the 1700s Spain had transitioned economic activity on the Saharan coast towards commercial fishing. After an agreement among the European colonial powers at the Berlin Conference in 1884 on the division of spheres of influence in Africa, Spain seized control of Western Sahara and established it