England, but also had to solve the problem of the existence side by
side of two great rival religions--Christianity and Mohammedanism.
Mohammedan invaders from Africa had secured political control of nearly
the whole peninsula as early as the eighth century, but in course of
time there appeared in the northern and western mountains several
diminutive Christian states, of which the following may be mentioned:
Barcelona, in the northeast, along the Mediterranean; Aragon, occupying
the south-central portion of the Pyrenees and extending southward
toward the Ebro River; Navarre, at the west of the Pyrenees, reaching
northward into what is now France and southward into what is now Spain;
Castile, west of Navarre, circling about the town of Burgos; Leon, in
the northwestern corner of the peninsula; and Portugal, south of Leon,
lying along the Atlantic coast. Little by little these Christian states
extended their southern frontiers at the expense of the Mohammedan
power and showed some disposition to combine. In the twelfth century
Barcelona was united with the kingdom of Aragon, and a hundred years
later Castile and Leon were finally joined. Thus, by the close of the
thirteenth century, there were three important states in the peninsula
--Aragon on the east, Castile in the center, and Portugal on the west--
and two less important states--Christian Navarre in the extreme north,
and Mohammedan Granada in the extreme south.

While Portugal acquired its full territorial extension in the peninsula
by the year 1263, the unity of modern Spain was delayed until after the
marriage of Ferdinand (1479-1516) and Isabella (1474-1504), sovereigns
respectively of Aragon and Castile. Granada, the last foothold of the
Mohammedans, fell in 1492, and in 1512 Ferdinand acquired that part of
the ancient kingdom of Navarre which lay upon the southern slope of the
Pyrenees. The peninsula was henceforth divided between the two modern
states of Spain and Portugal.