The employment of imperialism, through the expansion of empires, and the concept of political sovereignty, as developed after the Treaty of Westphalia, also explains the emergence of self-determination during the modern era. During, and after, the Industrial Revolution many groups of people recognized their shared history, geography, language, and customs. Nationalism emerged as a uniting ideology not only between competing powers, but also for groups that felt subordinated or disenfranchised inside larger states; in this situation, self-determination can be seen as a reaction to imperialism. Such groups often pursued independence and sovereignty over territory, but sometimes a different sense of autonomy has been pursued or achieved.