Slovaks make the biggest group in the country well above 80% of the population. The second largest group are Hungarians living in the belt along Hungarian borders from Nove Zamky in the south to Trebisov in the east. The make about 10% of the population or 500,000. Czechs are insignificant minority in the country, mostly located in Bratislava, and couple larger cities, making around 1% of the population or even less. The numbers are somewhere between 30,000 and 50,000 people. Majority of the Czech population left Slovakia in 1990's due better economic condition in Czech Republic, higher wages, and more liberal attitude. Third big group in Slovakia are Roma, especially in the east and northern Slovakia along the Tatra mountains and Low Beskids, who make up to 250-350 thousand people. Last significant ethnic minority are Ruthenians (Rusinians), who are NOT Russians, but Slavic people whose central region is in Carpathian region of the Western Ukraine, called Zakarpatia or Subcarpathian Ukraine.
In the past, there were other minorities like Germans, located in the mining cities in Central Slovakia, but almost none of them survived. Most of theme were expelled in 1946 or left after 1968 and 1989 when immigration to Germany for ethnic German was possible. Small group of Poles also lived in the area in Orava and Spis with borders of Poland and was a cause of the Slovak-Polish war in 1939. Bratislava in the past was a capital of the Royal Hungary, when Buda was under Ottoman control. There was a significant number of French, Italian, and Dutch merchants in the medieval times. In Renaissance, many Italians lived in Central Slovakia around Banska Bystrica and Kremnica, and many French Huguenots had settled in the 17th century at Western Slovakia around cities Skalica, Halic and Malacky, but eventually became assimilated or left to USA in the 1800's.