The capital of the powerful taifa Toledo has fallen into the hands of the army of King Alfonso VI in the year 1085. What seemed an insurmountable wall, has succumbed after a long siege, which lasted for some time that some figures in six or seven years, after which the Muslims were forced to capitulate by starvation. This conquest was but the culmination of the Spanish King's correrías across the border, which led him to making important places as Avila, Segovia, Salamanca Castilla, or Coimbra in Portugal.
The neighboring powerful taifas of Badajoz, Seville, viewed with great fear for their future, with the overwhelming Christian progress. Viéndose unable to contain its own forces conquering the tide, decided to request urgent assistance to the Almoravids, after extending his empire by the current Morocco, had established its capital in Marrakech. The king of Seville, sent emissaries to Marrakesh, viemdo almorávides in this call for help, the opportunity to take power in the rich and fertile territory of the Iberian peninsula and expanded by the West. So even with resistance from some taifas, new invaders are made with power in the land of Al Andalus, arriving later struck major feuds Castellanos.

Both sides had clear the importance of the moment, and the need to maintain a pulse to determine its supremacy, which led to the boundary line be moved south and was recovered part of the territories conquered by Castilla, Leon and Portugal. In Toledo concentrated troops Castellanas supported by Aragon and Catalonia expectant before the Almoravid progress. These supported by the kings of Seville, Badajoz and Grenada, were found in the town of Zalaca, the current Sagrajas near Badajoz and banks of the Guadiana. On October 23, 1086 the armies commanded by Alfonso VIII launched a sudden attack against the headquarters of Yusuf, which had changed its location so stealthy, encountering forces andalusíes from taifas Sevillana and Badajocense. The meeting was violentísimo, causing a terrible death in the ranks Muslim unable to stem the tide Christian. In short time disorder and confusion led to a widespread flight almost Arabs who stood with their backs to the Guadiana River.

From its strategic location, Yusuf ibn Tasfin waited to "kill two birds with one stone." Posibilitó extermination of the taifas forces and the attackers wore Christians. Let's defeat of taifas andalusíes to intervene when Christians were exhausted after their victory. When Alvar Fáñez, Alferez Real and commander Christian celebrated his victory, he was hit by the bulk of the army attacked the Almoravid side of disorderly army Christian sorprendiéndolo with a violent attack with a atronador sound of hundreds of drums. The chaos was all the dead being the most graceful, as the wounded and prisoners were treated cruelly, with their throats slit and their heads displayed as a trophy and a warning for all places and for a long time. The capture of the Spanish king was an order of priority of Yusuf their commanders, but he took refuge in a rugged hill protected by his personal bodyguard. Malherido heroically and protected in their flight decimated by their hosts, managed to leave the battlefield in the direction of Caceres, where after replacement forces, he fled and upheld in the town of Coria.