During the 18th century there was a lot of romantic nationalism in Europe that played significant role creating modern nation states in Europe. Countries were looking for legitimacy to exist and unity, So language, traditions, foklare, for epic, music and etc, When have something deeper rooted it creates a sense of Honors. Something for leaders to live up to.
The issues with colonialism it interrupted something organic. So if you look at a lot of modern African nations their ethnogenesis is the border were just drawn this ways, and cultural means nothing. And with detachment paves more way to division and corruption. Trying live up countries that only exist because they wanted independence from Europe and that greatest thing that bring unity. It's not like trying live up 200 to 500 or even thousand years cultures.
As before stated from 1750 to 1920's there was a lot changes in European borlders.
1789, French Revolution
1804–15, Serbian Revolution against the Ottoman Empire
1814, Norwegian independence attempt against Denmark-Norway and future Sweden & Norway, aftermath of the Napoleonic Wars (including War on independence)
1815, Congress of Vienna
1821-29, Greek War of Independence against the Ottoman Empire
1830, Croatian national revival
1830-31, Belgian Revolution
1830-31, Revolution in Poland and Lithuania
1846, Uprising in Greater Poland
1848, Nationalist revolts in Hungary, Italy and Germany (including Polish revolt in Greater Poland)
1859, Romania unified
1859-61, Italy unified
1863, Polish national revolt
1866-71, Otto Von Bismarck unifies Germany
1867, Hungary granted autonomy
1867, Irish Fenian uprising
1878, Congress of Berlin: Serbia, Romania and Montenegro granted independence, after they won the war against the Ottoman Empire
1905, Slav nationalism gathers force in the Habsburg and Ottoman Empire
1905, Norway becomes fully independent from United Kingdoms of Sweden and Norway
1908, Bulgaria becomes independent
1912, Albanian national awakening Albania becomes independent
Historically Italy was divided into Different kingdoms. There were different variance of Italian dialects, history and etc, but They share Italian cultures.
Like Wise while there a lot of different cultures and languages in Africa, a lot of it is sub groups and languages belonging to a larger culture.
Yorubaland expend Benin, Nigeria and Togo, Yorubaland was historically divided into different kingdoms and city-States. Oyo Kingdom, Benin Kingdom and etc. If Africa was never colonized Africa you had unification of Some cultures and a lot of states, taking over smaller ones. but borlders they would drawn base on cultures.
https://upload.wikimedia.org/wikiped...est_Africa.jpg
And that Just Yorubaland imagine if there was unification of Swahili cultures.
Also there would been more historic land marks and etc. In Cities like Benin, Kumasi and etc. Colonialization not only destroyed a lot in Africa especially during the invading wars. but a lot of the infrastructure build by the British was not towards modernizing African cities, but towards mines and ports they build, This is why places like Norirbi grew instead of Swahili Settlements. because the infrastructure was not built to benefit Africa but there own self interests.
https://c2.staticflickr.com/4/3276/2...06778fa0_b.jpg
https://c1.staticflickr.com/6/5067/5...274e0ea0_b.jpg