is one piece episode 172 filler?

The battle still continues between the Shandia warriors and Divine Soldiers. Robin, still in the ruins, explores it.

She finds a monument which she commented must have been erected after the city fell and she found out that the name of the ancient city is called Shandra. Robin continued to make notes of what she had learned regarding Shandra; she said herself that she would continue to explore and may find some clue to the True History, which she could not find on the sea below.

Just as she was observing and taking notes, Yama appeared.