Is there a way to "win" in Mount and Blade?

You 'win' when you decide that you've achieved what you wanted and have had enough. Even if you conquered the whole world, I expect you could simply start another rebellion and conquer it again.

It's a great game, but I suspect you will tire of it before you get anywhere near taking over the whole land.

Just enjoy playing it. If you find you are progressing too fast, notch up the difficulty, or impose restrictions on yourself (swords-only, or no horses etc)

Mount & Blade is a "sandbox" game, which means that it's more of a simulation than a typical game. There is no end goal, no ultimate win condition. This can be very frustrating at times, because you never know if you "should" be doing this or that. But that's also one of the most beautiful aspects of the game. You are in complete control of your destiny, free to set your own goals and develop your own strategies.

If you're feeling lost or confused, leave your faction, finish/abandon all your quests, and disband your entire army. Then wander the map alone for a while like a monk with his staff. I did this just yesterday, and it gave me a fresh perspective, a new strategy.

I conquered the whole land and destroyed all but two of the factions which have no territory or lords to their name. Basically there is no winning animation or anything just and achievement if you are playing through steam. Otherwise eventually all the factions disappear and you are left in control and you could keep playing if you wanted but really all thats left are bandits to kill so have fun and start a new playthrough using different weapons and strategies this time.