几千年以前的英语

thousand years ago即可

这个简单嘛 千百年前

many thousand years ago

thousands of years ago（千年之前）或者直接back in the old days（在以前）

一千年以前 [网络] A Thousand Years Before; One Thousand Years Ago; [例句]不列颠人在英格兰土地上看到敌人的营火，已经是将近一千年以前的事了。It was nearly a thousand years since Britain had seen the fires of a foreign camp on English soil.

Nineteen Ninety-nine.Nine Ninety-seven.

several thousand years ago thousand years agohousands of years ago