Actually, if your saying the timeline roughly started at or around the time of the first men and the invasion of the Andels, this would be the rough equivalent of the bronze age, and legend transfers it into the iron age. As to the actual period of time that elapsed between the long night, and current date/time in which the story is set, there is a great deal of uncertainty.
" According to tradition, Jeor Mormont was the 997th Lord Commander of the Night's Watch - according to the legend that the Watch was founded a full 8,000 years ago, when the Wall was allegedly constructed. Samwell Tarly points out that they have no real way of knowing if there have actually been 997 Lords Commander, or even if the Watch is truly 8,000 years old. While reading through the Castle Black library, Samwell says that the most complete list of Lord Commanders he ever found only consisted of 667 names - and he has no way of confirming if dozens if not hundreds of those names were ever real men, or simply legendary figures who were later added into the lists. While Mormont is still considered the 997th Lord Commander, there are simply huge gaps in the list, with allegedly 330 Lords Commander whose names have simply been forgotten. It isn't clear exactly how far back in time an accurate historical count extends: history becomes relatively accurate after the Targaryen Conquest, but it hasn't been stated what number the Lord Commander at the time (Harren the Black's brother) was."
What I am getting at is recorded history suggests that it is closer to 2000-3000 years, and so, things aren't progressing as slowly as you might think.
