The written Czech language started to penetrate into present-day Slovakia through Czech clergy teaching in capitular schools in the 14th century. In the pre-standard period, the Czech language was used along with Latin and cultural Slovak as a cultural and liturgical language. The reasons for the use of the Czech language were the absence of a uniform Slovak language standard due to the absence of a Slovak state, whereas the Czech was a standardized language; the rise of the Slovak population in towns; the similarity to Slovak making it easier to learn; studies of many Slovaks at the University of Prague; the influence of the campaigns of the Czech Hussites and of John Giskra (Ján Jiskra) in Slovakia; and the temporary conquest of Moravia by the Hungarian king Matthias Corvinus.