I know there are a lot of people thinking about this basic and interesting question, and a lot of intelligent theories.

I would like to introduce some of my thoughts on the subject, and hear other opinions as well.

First of all, as far as I understand, the gun did not outperform the bow in accuracy or range until the advent of rifling in the 19nth century.

It makes sense to me that effective bows have always been cheaper and easier to make than effective guns (I have made effective bows and arrows by hand, and they don't take many resources).

Arrows may be more expensive to produce than bullets, but arrows can and have been reused throughout all of history. People could scavenge battle zones to recollect arrows, and in my experience, a single arrow can easily survive a few thousand shots into a firm target.

I have heard it takes more training to become a good archer, than a good gunman... Is this really true or just an easy assumption?

That could be a reasonable assumption to a certain degree, but I think there is a lot of over-estimation about how much training archery requires. I have been shooting bows since I was twelve, but never did heavy training until I was 18, and I guarantee I was shooting apples at 20 yards after only a few weeks of heavy training.

I'm not sure if bows really take any more time to train with than guns, I think the real difference is that bows simply require more strength and dedication to master... to undergo the more physically challenging training (sore bodies and bloody fingers come to memory).

Maybe it wasn't about how long it took to train archers vs gunmen... Maybe it was just the physical requirements? Maybe guns are simply easier for those that aren't interested in the commitment of practicing a martial art and focusing on muscle training?

Finally, I have heard some interesting ideas about guns replacing bows because guns fit into more mobile battle tactics.

I'm not sure how much I understand that however... Archers don't have to be stationary or immobile. I know from experience and observation that archers can engage in mobile tactics, involving continual shooting on the run, and certainly while rushing from cover to cover. Archers could charge, shoot, and retreat, all in quick motions. I'm not currently convinced that guns have any particular advantages in mobility, especially considering guns are heavier than bows, and suffer from roughly the same difficulties on the run.

I'm sure I left out some good points, so fill me in!!! :)