Třinec is a city in Frýdek-Místek District in the Moravian-Silesian Region of the Czech Republic. It has about 34,000 inhabitants and is the least …Třinec is a city in Frýdek-Místek District in the Moravian-Silesian Region of the Czech Republic. It has about 34,000 inhabitants and is the least populated statutory city in the country. The city is an important cultural centre of the Polish minority in Trans-Olza, which makes up 12.1% of the population.