The country of Ecuador also includes the Galápagos Islands (made famous by Darwin), which is about 1,000km west of the mainland. A variety of smaller groups were gradually incorporated into the Inca Empire during the 15th century, which was possibly the largest empire in the world at the time. When the Incas arrived, some of the existing developed confederations took a couple of generations to incorporate. Problematic groups were deported to areas that now make up Peru, Bolivia and Northern Argentina. The Inca Empire was conquered by Spain, with Ecuador becoming an independent state with an ethnically diverse population in 1830. Most of its population of about 16 million people are of mixed descent.