Two major mountain ranges populate Poland's south-east and south-west borders, respectively: the Sudetes and Carpathian Mountains mountain ranges. Those ranges are located both within and outside of Poland. Within Poland, neither of them is forbidding enough to prevent substantial habitation; the Carpathians are especially densely populated. The rugged form of the Sudeten range derives from the geological shifts that formed the later Carpathian uplift. The Carpathians in Poland, formed as a discrete topographical unit in the relatively recent Tertiary Era, are the highest mountains in the country. They are the northernmost edge of a much larger range that extends into the Czech Republic, Slovakia, Ukraine, Hungary, and Romania.
The Świętokrzyskie Mountains, one of the oldest mountain ranges in Europe, are located in central Poland, in the vicinity of the city of Kielce. The mountain range consists of a number of separate ranges, the highest of which is Łysogóry (lit. bald mountains). Together with the Jura Krakowsko-Częstochowska the mountains form a region called the Lesser Poland Upland (Wyżyna Małopolska). They were formed during the Caledonian orogeny of the Silurian period and then rejuvenated in the Hercynian orogeny of the Upper Carboniferous period.