The Czech lands (in Czech: České země) or Czechia (in Czech: Česko) is an auxiliary term used for Bohemia + Moravia + Czech part of Silesia + other territories that were parts of the Kingdom of Bohemia (Lands of the Bohemian/Czech Crown) at the particular time in history (e.g. Lusatia, Brandenburg), today identical with the Czech Republic. It is used especially for the period till 1969 (when the entity and term Czech Socialist Republic arose), but also afterwards.

Czech lands was used especially in the past (before 1992), when the alternative term Czechia was used rarely (in Czech it was codified in 1777, but was rarely used both in the Czech and in the English language), so that it was impossible to describe the main and secondary Czech territory by one word. The use of the term Czechia was officially endorsed by the Czech Republic at the time of its establishment around 1993 (see Czech Republic) and there has been a special meeting of the Czech Senate (Upper Chamber of the Parliament) in the summer of 2004 where experts advocated the use of the short form even in English. Also, Czech authorities increasingly use the form "Czechia" in their official English-language documents (not always however).

The Czech equivalent for Czechia / Česko, after a slow start, is used more and more often by Czech speakers, newspapers, etc. Although in informal conversation, the Czech equivalent for Bohemia / Čechy is probably more common. However, Moravians would strongly object to Bohemia being "more" than another part of Czechia. Next, the Silesian certainly want to be treated as another part of Czechia, and not "included in" Moravia and/or Bohemia.