Polish has two verbs for "drink" - one imperfective (pić) and one perfective (wypić). The problem is that English Past Simple not always carries the meaning of doing something completely/finishing it. Therefore we can say that English Past Simple covers partially semantic space of "pić" and partially of "wypić".
They certainly emptied the container in which your wine was hold, whether that was bottle, glass, barrel or something else.
Aspect works somehow differently for pić/wypić pair – in past tense we understand both as done, but the difference is instead in the amount of fluid drank; if something is left after the action, „Oni pili”; if the container was emptied, „Oni wypili”.