What is the basis of national identity and nationalism and how did governments use these new ideas on their populations?

Nationalism is defined as "a belief in the importance of one's nation, stemming from its unique laws, language, traditions, and history" (Crossroads and Cultures). It first emerged during the Enlightenment period, when people began to come together as a nation and to take pride in their culture. To build national identity, some looked to traditions of the past. For example, old works of literature such as poems were imitated by modern poets and were also recited by children in school. Another symbol of national unity was the leader of the country and the country's flag. The history of a nation was also an effective unifier, and leaders utilized this through monuments, parades, theatrical productions, and museums. However, people were prone to overlook the bloody details of their nation's past and instead focus more on the romantic details of their "founding fathers."
Below is a picture of the Korean flag first created in the 1880's. The Korean rulers wanted a flag that represented all of their peoples, something behind which Koreans could rally. The flag accomplishes this through the balance of yin and yang (depicted in the middle) and the four elements of water, fire, earth, and air.

Some governments sought national unity through a homogeneous culture, but others embraced cultural diversity. The Russian Empire attempted to force all of their peoples into adopting the Russian language and Orthodox religion. Contrastingly, the United States accepted and even celebrated African American musical innovations, such as blues and jazz. Both of these music genres have their roots in African music.