@jakubzelenka Well, the word ‘Czechia’ is used without an article. https://www.oxfordlearnersdictionaries.com/definition/english/czechia
czechia noun - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com

Definition of czechia noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.