以前，⋯⋯
yǐ qián,……
Expressing "before" in general with "yiqian"
以前 at the front of a sentence means "in the past", with no specific point attached.
以前，+ Clause
How it works
以前，我不会说中文 — I couldn't speak Chinese before. Standing alone at the start, 以前 covers the whole of the past.
This is the same word that means "before X" when it follows a time or an action. What changes is the position: after something it's relative, at the front it's absolute.
以前 pairs naturally with 现在 for a before-and-after contrast.
Examples
yǐ qián, wǒ bú huì shuō zhōng wén
以前，我不会说中文。
I couldn't speak Chinese before.
yǐ qián zhè lǐ shì yì jiā shū diàn
以前这里是一家书店。
This used to be a bookshop.
yǐ qián wǒ cháng cháng qù, xiàn zài bú qù le
以前我常常去，现在不去了。
I used to go often; I don't anymore.