Back to the list of units The Chu-Ko-Nu is one of the strongest ranged attackers of the Medieval Era, thanks to its ability to fire twice in a round even before it reaches a high enough level to.
Civ 5 Gatling Guns
The Civilization 5 manual does not have such a chart, and neither is there one in the game like the tech tree. (I do not know if the physical copy of the game comes with any charts.)However, you can use the Civilpedia to build one. Look up whichever unit you are concerned about. The Civilpedia will show what it upgrades to, which you can click on to get to that unit, and follow that unit in turn.General trends.
Units can usually upgrade within their type: Melee to Melee, Range to Ranged, Mounted to Mounted, Siege to Siege. Except that Melee and Ranged eventually upgrade to the same Gunpowder track. Melee is split into (at least?) two upgrade paths: one for the anti-mounted Spearmen-Pikemen, and the other for the general units. I believe missiles do not upgrade?