Final answer:
True, nationalism predated the development of the nation-state, with nationalistic sentiments existing even within multi-national empires. Figures like Herder promoted nationalism for peace, but it also led to exclusion and conflict. The concept enriched political movements that eventually saw the creation of modern nation-states.
Step-by-step explanation:
True, nationalism existed before the development of the nation-state. Nationalism is a sense of pride and devotion to one's nation, often based on shared attributes such as blood, history, or soil. The ideology of nationalism promotes the idea that people with a common national identity should have their state.
In the era before modern nation-states, empires comprised multiple national groups, and the rise of nationalist sentiment posed a significant threat to their cohesion. Notable figures like Johann Gottfried von Herder have defended nationalism, viewing it as a path to international peace if each nation celebrated its uniqueness. Nonetheless, nationalism has also fueled social exclusion and conflict when it was used to profess the superiority of one nation over others.