Pachacuti 's son, Topa Inca continued the empire 's military expansion

and he eventually became ruler in 1471 CE.

By the end of his reign, the empire covered much of western South America.

Topa 's son Huayna Capac succeeded him in 1493,

but the new ruler 's distant military campaigns, strained the social fabric.

And in 1524, Huayna Capac was stricken by fever.

Spanish Conquistadors had arrived in the Caribbean some time before,

bringing diseases to which the native peoples had no resistance.

Millions died in the outbreak, including Huayna Capac and his designated heir.

The vacant throne ignited a civil war between two of the surviving brothers,

Atahualpa and Huascar, greatly weakening the empire.

In 1532, after finally winning the Inca civil war, Atahualpa and his army encountered the European invaders.

Although greatly outnumbered, Francisco Pizarro and his small group of conquistadors,

stunned the king 's much larger force with guns and horses,

neither of which they had seen before.

Atahualpa was taken captive and killed about a year later.

The Spanish conquerors were awed by the capital of Cuzco.

Pizarro described it as so beautiful that it would be remarkable even in Spain.

Though the capital had fallen, and the native population had been destroyed by civil war and disease,

some Incas fell back to a new capital at Vilcabamba, and resisted for the next 40 years.

But, by 1572, the Spaniards had destroyed all remaining resistance,

along with much of the Inca 's physical and cultural legacy.

Thus, the great Inca empire fell even faster than it had risen.