Learn German: Früher gab es keine Unordnung. - In the past, there was no mess.

The base word is die Ordnung, which means order, tidiness, or organization. Adding the prefix Un- creates its exact opposite. So, Unordnung translates to disorder, untidiness, or a mess. It is a very useful prefix that you can attach to many nouns and adjectives to mean the opposite of something, much like the prefix un- does in English.

Since Unordnung already has a negative prefix, why do we need keine? Doesn't that make it a double negative?

The Un- prefix creates a new, independent noun (die Unordnung meaning the mess). It changes the vocabulary word, but it doesn't grammatically negate the sentence. To say there was no mess, you still have to negate the noun in the sentence. Since we are negating a noun, we use the negative article keine.

Why is the word order gab es instead of es gab?

This is because of the verb-second rule. The sentence starts with the time adverb Früher (in the past). Because the conjugated verb (gab) must always take the second position in a standard main clause, the subject (es) gets pushed to the third position, right after the verb.

What is the base form of gab es?

It comes from the fixed phrase es gibt, which means there is or there are. The verb gab is the simple past tense (Präteritum) of geben. Therefore, es gab simply means there was or there were.