The first inhabitants of the Czech lands were prehistoric fish. That's because the country, at the time, was covered by a prehistoric ocean - thanks to which it is possible to find some very nice fossils of trilobytes in the Czech Republic today.
Today's Czech Republic was later populated by dinosaurs of all sorts, and later by neanderthals and even by mammoths. The prehistoric settlement of the present-day Czech Republic by people culminated in the fourth century B.C. with the arrival of the Celts, the first modern human inhabitants of this territory that we know of. In fact, the Latin name for the Czech lands, "Boiohaemum" (Bohemia), is derived from the name of the Boii Celtic tribe; and the Czech name for the Moldau River (which flows through the capital city of Prague) is Vltava - which is said to come from the Celtic "Vlt" meaning wild, and "Va" meaning water.
Of no relation to any of this is Brighter By The Hour, who emerged suddenly onto the scene out of apparent nothingness. They love long walks on the beach, toast, and fresh socks.