130. The Mohammedan conquest served to make the history of Spain very different from that of the other states of Europe. One of its first and most important results was the conversion of a great part of the inhabitants to Mohammedanism.[253] During the tenth century, which was so dark a period in the rest of Europe, the Arab civilization in Spain reached its highest development. The various elements in the population, Roman, Gothic, Arab, and Berber, appear to have been thoroughly amalgamated. Agriculture, industry, commerce, art, and the sciences made rapid progress. Cordova, with its half million of inhabitants, its stately palaces, its university, its three thousand mosques and three hundred public baths, was perhaps unrivaled at that period in the whole world. There were thousands of students at the university of Cordova at a time when, in the North, only clergymen had mastered even the simple arts of reading and writing. This brilliant civilization lasted, however, for hardly more than a hundred years. By the middle of the eleventh century the caliphate of Cordova had fallen to pieces, and shortly afterwards the country was overrun by new invaders from Africa. [Sidenote: The rise of new Christian kingdoms in Spain.] Meanwhile the vestiges of the earlier Christian rule continued to exist in the mountain fastnesses of northern Spain. Even as early as the year 1000,[254] several small Christian kingdoms--Castile, Aragon, and Navarre--had come into existence. Castile, in particular, began to push back the demoralized Arabs and, in 1085, reconquered Toledo from them. Aragon also widened its bounds by incorporating Barcelona and conquering the territory watered by the Ebro. By 1250, the long war of the Christians against the Mohammedans, which fills the mediæval annals of Spain, had been so successfully prosecuted that Castile extended to the south coast and included the great towns of Cordova and Seville. The kingdom of Portugal was already as large as it is to-day. [Sidenote: Granada and Castile.] The Moors, as the Spanish Mohammedans were called, maintained themselves for two centuries more in the mountainous kingdom of Granada, in the southern part of the peninsula. During this period, Castile, which was the largest of the Spanish kingdoms and embraced all the central part of the peninsula, was too much occupied by internal feuds and struggles over the crown to wage successful war against the Moorish kingdom to the south. [Sidenote: Marriage of Isabella of Castile and Ferdinand of Aragon.] [Sidenote: Granada, the last Moorish stronghold, falls.]