In short very modern. But first a few quick qualifiers if by voting you mean the modern style proportional representation model we are accustomed to and not a semi-direct democratic delegation method like what see with the Haudenosaunee (and other societies) as far back as maybe the 1100’sCE^1. And if by “universal suffrage” you mean that the proportional representation model being discussed is extended to all persons regardless of race, gender, class, creed etc who are living in a given nation-state or society then we narrow our options considerably. We narrow it so much that most modern nations, including the United States with its four million plus territorial subjects who can not vote in federal elections will fail pass our criteria. With that in mind the first nation in history that instituted universal suffrage for its citizens was New Zealand in 1889^2 with the ending of plural voting for men^2 (giving men multiple votes) which followed the earlier expansion of voting rights to all citizens^2. Here's a neat fact the Maori who are the native people of New Zealand actually got male voting rights before white men^2, neat right? Also I feel like it is important to mention that all of this does not include the myriad of arguments about how modern democracy is still very far from true universal suffrage because of it's exclusion of young people^3, certain criminals^4, and the over representation of the wealthy^5 etc etc.

There were several medieval republics that existed^6 however most notable were Venice and Genoa, voting rights however were restricted to only certain types of men in their borders^6. And it was common in medieval societies for small communes or settlements to administer themselves in the form of popular assemblies provided they maintained the dues owed to feudal/local lords^7. It’s important to note here that medieval kingdoms were not states as we would think of them now where a citizen is part of a larger whole and they are party to what the state does or doesn’t do. Instead medieval societies were more like systems of interlocking loyalties and obligations with a given kings land being more of a list of people/settlements who are loyal to him rather than a territory his subjects have rights to^8. Finally there were also directly democratic institutions with universal or near universal suffrage that existed outside of nations prior to New Zealand, most notably on pirate ships^9. Hope this helps.

1. Mann & Fields 1997

2. Nohlen, Dieter (2001). Elections in Asia and the Pacific: South East Asia, East Asia, and the South Pacific.

3. Hyde, Martin (2001). Democracy education and the Canadian voting age.

4. Uggen, Christopher; Manza, Jeff (2002). "Democratic Contraction? Political Consequences of Felon Disenfranchisement in the United States"

5. Gilens, Martin & Page, Benjamin I. (2014). "Testing Theories of American Politics: Elites, Interest Groups, and Average Citizens"

6. Walton, Nicholas. Genoa, 'La Superba': The Rise and Fall of a Merchant Pirate Superpower.

7. Kropotkin, Peter (1902). Mutual Aid: A Factor of Evolution

8. Hechter, Michael (2000). Containing Nationalism

9. Cordingly, David. 1996. Under the Black Flag: The Romance and the Reality of Life Among the Pirates.