After the Mongol invasion in 1241–1242 many of the newly founded towns in the Kingdom of Hungary received the right to use the royal double cross as their coat of arms. The first, biggest and most towns of the kingdom arose in present-day Slovakia - the part of the kingdom that was characterized by German settlers, extensive mining activities and thus the most advanced economy at that time. It was probably partly due to this use in municipal coats of arm that the double cross became a clear symbol of the northern part of the kingdom again from the 15th century onwards and Upper Hungary from the 18th century.