The palaces of early Neo-Assyrian emperors were heavily episodic and could be considered comics. An example en brief:
Assyrian palace complexes, possessed wide and long hallways that were covered on either end by reliefs of some kind. There reliefs often depicted battles, deeds and events of supposed import. Delegates from afar or even local leaders, nobles, etc would be walked through the hallways on their journey to meet and prostrate before the King of the Universe (king of Assyria); these reliefs thus, had the use of tools of propaganda and speech that were to be conveyed to the walker in a episodic mode. As the person enters, they see a relief on their left, where the great king is affronted by the deeds of an enemy, walking further, the story continues where the king raises his army; following, he marches his army, collects grains, prays to the gods, takes omens and so forth. After this, the story continues as the man walks and he views that the king conquers the enemy, usually in battle, afterwards, the king sieges the city and conquers. In conclusion, the relief depicts the Assyrian army taking slaves, celebrating, returning to Kalhu, feasting and finally a prayer to the god(s) who helped the king achieve victory.
Another example, a relief in Ninevah in a palace, displayed the building of a statue. Each time the person walked many paces, a part would be added or something changed, until the final room, the statue was complete in all of its glory. This in effect is a proto-comic, as I understand it.
The issue with this system, was that to some, it created chaos. Namely, if a person was to walk through the hallway, if he stopped before one of the scenes had completed and turn around and walk outside, he would have in some way, nullified what was about to occur. A person could thus claim, that he did not see the victorious Assyria, rather he had stopped and walked away, undoing the action and creating doubt as to the grandeur of the king. Thus, Assyrian reliefs began to revert to older systems seen on Naram-Sin's relief, wherein the entire action is displayed in the same relief. Instead of there being many phases of the war, the entire war was shown in a single image. So, the king was raising soldiers at the same time as he was capturing the city and at the same time as he was celebrating victory and making offerings. If one is able to remove this stigma regarding Assyrian reliefs, we could have true comics develop far, far earlier.