Asheara is a female NPC from Diablo 2 who returns in Diablo 3. She looks much the same and still seems to be a mercneary captain, though she's now found in the desert Borderlands area, far from the jungles of Kurast.
She was seen in the Blizzcon 2009 demo, where she was the first NPC who players met when they began the demo. Standing in the Sundered Pass just outside the closed gates of Caldeum, Asheara gave players the main quest of the demo, to Find Alcarnus, a city on the other side of the desert that's become unreachable due to massive monster activity in the deserts.
Diablo 2
In Diablo 2, Asheara was the leader of a group of mercenaries - the Iron Wolves. They were the protectors of Kurast and prided themselves of being as tough as the jungle outside the town.
In Diablo 2, the Iron Wolves' home of Kurast was protected by magic, first by Hratli and then later by the once-powerful mage called Ormus who used the Gidbinn to forge a powerful Skatsimi spell. Given this, it seems unlikely that the city could have fallen in just 20 years especially since Mephisto, the demon responsible for the corruption of the area was slain and his soulstone was destroyed. However, it is possible that Kurast never recovered from it's near extinction, or perhaps the Iron Wolves decided that their talents would be more useful elsewhere. It is also possible that since the destruction of the Worldstone meant an end to demon attacks, that Asheara had to change businesses.
An Assassin temporarily located in Kurast Docks called Natalya thinks Asheara is more bark than bite, never having faced true Evil.