existíais
-you were existing
The word existíais is the imperfect form of existir in the second person plural.
See the full existir conjugation

existir

Antes de la llegada del monstruo azul, no existíais.
Before the arrival of the blue monster, they did not exist.
Antes de la llegada del monstruo azul, no existíais.
Before the arrival of the blue monster, you didn't even exist.
No sabía si realmente existíais.
I didn't know if you guys really existed. Flesh and blood.
Want to Learn Spanish?
Spanish learning for everyone. For free.
SpanishDict Premium
Have you tried it yet? Here's what's included:
Cheat sheets
No ads
Learn offline on iOS
Fun phrasebooks
Learn Spanish faster
Support SpanishDict