Passage: The Holy Roman Empire, which had included more than 500 independent states, was effectively dissolved when Emperor Francis II abdicated (6 August 1806) during the War of the Third Coalition. Despite the legal, administrative, and political disruption associated with the end of the Empire, the people of the German-speaking areas of the old Empire had a common linguistic, cultural, and legal tradition further enhanced by their shared experience in the French Revolutionary Wars and Napoleonic Wars. European liberalism offered an intellectual basis for unification by challenging dynastic and absolutist models of social and political organization; its German manifestation emphasized the importance of tradition, education, and linguistic unity of peoples in a geographic region. Economically, the creation of the Prussian Zollverein (customs union) in 1818, and its subsequent expansion to include other states of the German Confederation, reduced competition between and within states. Emerging modes of transportation facilitated business and recreational travel, leading to contact and sometimes conflict among German speakers from throughout Central Europe.

Question: what was one of the things that caused problems among German speakers in Central Europe?
transportation facilitated business and recreational travel