THE MOORISH CONQUEST 297 force, across the difficult and waterless deserts which had hitherto served as the best military defence of the Soudan.

When a military nation wishes to fight with one which it has reason to believe to be unprepared, a cause of quarrel is never far to seek. Morocco found its cause of quarrel with Songhay in the possession of the salt mines of Tegazza. It will be remembered that these mines lay upon the western road leading from Tafilet, or Sidjilmessa, to Ghana and Timbuctoo. Their position upon modern maps is about 8° W. by 26° N. They were within the limits of the Mellestine, and when the power of Songhay had succeeded to that of Melle, they were included in the territories of the Songhay Empire. They furnished the principal salt supply of the Soudan, and their possession was therefore a matter of supreme importance to Songhay. We have seen that during the sixteenth century the Sultans of Morocco had from time to time made efforts to dispute the supremacy of Songhay over this valuable border district, and that their claims had been vigorously rejected by the earlier Askias. It happened, in the year 1590, when the second Askia Ishak was on the throne of Songhay, and that of Morocco was occupied by Muley Hamed, that a certain Songhay official, who had been interned at Tegazza as a punishment for malpractices by a previous Askia, succeeded in effecting his escape, and fled across the northern border to the court of Morocco. He there represented to Muley Hamed the ease with which the conquest of Songhay, in the present condition of the country, could be effected, and he treacherously placed all his knowledge at the disposal of the enemy. As a consequence of these representations, Muley Hamed wrote to Askia Ishak, and announced that he proposed to invade his country, unless he were willing to transfer to Morocco the salt mines of Tegazza. The sovereign of Morocco urged that he had a right to possess the mines, since it was only thanks to his exertions that the country was defended and protected against the incursions of the Christians. Askia Ishak rejected