allowing grain to be grown using a center pivot irrigation system. A single well can provide 30 L/s to 50 L/s of water. In addition to water, the rock beneath Tuat contains pockets of natural gas. Sonatrach, the Algeria state-owned oil company, is collaborating with foreign companies in joint ventures to exploit these gas reserves. Sonatrach and the China National Oil & Gas Exploration & Development Corporation (CNODC) have constructed a refinery near the village of Sbaa, 40 km north of Adrar. This began operating in 2006. Separate projects led by Gaz de France (GDF Suez) and Total are both scheduled to start supplying gas in 2013. A pipeline is being built to connect to Hassi R'Mel. To the north of Tuat is Gourara, a similar region also containing oases with date palms irrigated by foggaras. The largest town, Timimoun, is 162 km north east of Adrar. History The Tuat oases were important in the trans-Saharan trade because of their location at the northern end of the Tanezrouft route. Reggane is around 1150 km north of the town of Gao and a similar distance from Timbuktu. Caravans from the Sudan would continue northwards to towns such as Sijilmasa or Tlemcen. The oases are not mentioned by any of the early Arabic geographers, but it appears that Jews lived in the oases at an early date as a tombstone discovered in a village of the Bouda region has an inscription in Hebrew with a date of 1329. The earliest written reference to Tuat is by Ibn Battuta. He visited Bouda in 1353 after crossing the Sahara from Takedda in present-day Niger, a distance of 1390 km. He travelled with a large caravan that included 600 slave girls. He wrote: "Then we arrived at Būda, which is one of the biggest villages of the Tuwāt. Its land consists of sand and salt pans. It has many dates which are not good, but its people prefer them to the dates of Sijilmāsa. There is no cultivation there nor butter nor oil. Oil is only imported to it from the land of the Maghrib. The food of its people is dates and locusts. These are abundant with them; they store them as dates are stored and use them for food. They go out to hunt them before sunrise, for at that time they do not fly on account of the cold." Ibn Battuta stayed