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Early conquests

In the early 1050s, a kind of triumvirate emerged in leading the Almoravid movement, including Abdallah Ibn Yasin, Yahya Ibn Umar and his brother Abu Bakr Ibn Umar. The movement was now dominated by the Lamtuna rather than the Guddala. During the 1050s, the Almoravids began their expansion and their conquest of the Saharan tribes. Their first major targets were two strategic cities located at the northern and southern edges of the desert: Sijilmasa in the north and Awdaghust in the south. Control of these two cities would allow the Almoravids to effectively control the trans-Saharan trade routes. Sijilmasa was controlled by the Maghrawa, a part of the northern Zenata Berber confederation, while Awdaghust was controlled by the Soninke. Both cities were captured in 1054 or 1055. Sijilmasa was captured first and its leader, Mas'ud Ibn Wannudin, was killed, along with other Maghrawa leaders. According to historical sources, the Almoravid army rode on camels and numbered 30,000, though this number may be an exaggeration. Strengthened with the spoils of their victory, they left a garrison of Lamtuna tribesmen in the city and then turned south to capture Awdaghust, which they accomplished that same year. Although the town was mainly Muslim, the Almoravids pillaged the city and treated the population harshly on the basis that they recognized the pagan king of Ghana.

Not long after the main Almoravid army left Sijilmasa, the city rebelled and the Maghrawa returned, slaughtering the Lamtuna garrison. Ibn Yasin responded by organizing a second expedition to recapture it, but the Guddala refused to join him and returned instead to their homelands in the desert regions along the Atlantic coast. Historian Amira Bennison suggests that some Almoravids, including the Guddala, were unwilling to be dragged into a conflict with the powerful Zanata tribes of the north and this created tension with those, like Ibn Yasin, who saw northern expansion as the next step in their fortunes. While Ibn Yasin went north, Yahya Ibn Umar remained in the south in the Adrar, the heartland of the Lamtuna, in a defensible and well-provisioned place called Jabal Lamtuna, about 10 kilometres northwest of modern Atar. His stronghold there was a fortress called Azuggi (also rendered variably as Azougui or Azukki), which had been built earlier by his brother Yannu ibn Umar al-Hajj. Some scholars, including Attilio Gaudio, Christiane Vanacker, and Brigitte Himpan and Diane Himpan-Sabatier describe Azuggi as the "first capital" of the Almoravids. Yahya ibn Umar was subsequently killed in battle against the Guddala in 1055 or 1056, or later in 1057.

Meanwhile, in the north, Ibn Yasin had ordered Abu Bakr to take command of the Almoravid army and they soon recaptured Sijilmasa. By 1056, they had conquered Taroudant and the Sous Valley, continuing to impose Maliki Islamic law over the communities they conquered. When the campaign concluded that year, they retired to Sijilmasa and established their base there. It was around this time that Abu Bakr appointed his cousin, Yusuf ibn Tashfin, to command the garrison of the city.

In 1058, they crossed the High Atlas and conquered Aghmat, a prosperous commercial town near the foothills of the mountains, and made it their capital. They then came in contact with the Barghawata, a Berber tribal confederation who followed an Islamic "heresy" preached by Salih ibn Tarif three centuries earlier. The Barghawata occupied the region northwest of Aghmat and along the Atlantic coast. They resisted the Almoravids fiercely and the campaign against them was bloody. Abdullah ibn Yasin was killed in battle with them in 1058 or 1059, at a place called Kurīfalalt or Kurifala. By 1060, however, they were conquered by Abu Bakr ibn Umar and were forced to convert to orthodox Islam. Shortly after this, Abu Bakr had reached as far as Meknes.

Towards 1068, Abu Bakr married a noble and wealthy Berber woman, Zaynab an-Nafzawiyyah, who would become very influential in the development of the dynasty. Zaynab was the daughter of a wealthy merchant from Kairouan who had settled in Aghmat. She had been previously married to Laqut ibn Yusuf ibn Ali al-Maghrawi, the ruler of Aghmat, until the latter was killed during the Almoravid conquest of the city.