If you are looking for a description of what the game was like at this stage:
If you are trying to play with mods , many older mods were built specifically for v1.5.8, which is why some players still keep this exact version installed today. Mount.&.Blade.II.Bannerlord.v1.5.8.263439.GOG.p...
Introduced as a standalone way to play without the "Dragon Banner" questline. If you are looking for a description of
It looks like you're referring to a specific version of (v1.5.8), likely a build from the GOG platform. "Mount & Blade II: Bannerlord v1
"Mount & Blade II: Bannerlord v1.5.8 was a major update in the game's journey toward its 2022 full release. This version focused heavily on stabilizing the sandbox experience, introducing the which allowed players to start their journey without the constraints of the main storyline. It also brought significant improvements to the battle terrain system , ensuring that the maps players fought on more accurately reflected their position on the world map, and added several new armor sets and weapon balances to the Calradian frontier." 2. Technical / Patch Note Highlights
Since you mentioned a specific file string format, if you are looking for help with a technical issue or installation for this specific version, please let me know!