> Pitched battles were far more common in the ancient world (think Persia, Macedon, Rome, etc) – this is a product of the larger size and greater organizational capabilities of those armies.
Consequently also in antiquity, most engagements where sieges rather than set piece battles.
The whole "battles were rare, sieges where common" is a trope I believe some YouTubers started, but I don't think there's any solid pattern. Ancient armies pillaged the countryside to provoke encounters. Steppe peoples did pitched battles all the time because they didn't build walls. Medieval Europe may have had more sieges than battles because of religious homogeneity, but you can see how that model falls down soon in the thirty years war: if you don't engage the enemy they'll loot and pillage you to oblivion. Your people see how you are unable to protect them and desert you.
Another distinguishing factor is the widespread building of castles. During the classical era, fortifications were less useful because there were powerful states that could capture them anyway. But when even the nominal king or emperor had trouble mustering a force of fifty thousand men, the castle vs. the siege (and the raid) dominated most warfare. During the classical area many of those same places would have been sparsely populated, and certainly not well fortified.
Defensive structure really only made sense in specific border regions. There however large empires certainty did invest in such defenses. Border cities that were ready to be under siege and that could host an arriving army.