Why does the psalmist start by recalling God's past actions in Egypt? It's more than just a history lesson.
Psalm 78 is a "maschil," a teaching psalm. Its purpose is to instruct the "my people" (v. 1) about God's faithfulness and Israel's repeated unfaithfulness. The psalmist emphasizes that history isn't just a random series of events; it's a divinely orchestrated narrative meant to be passed down. Recounting God's "wonders" isn't about boasting in human achievement, but about revealing God's character and power. This practice aims to foster awe, obedience, and trust in the present generation, learning from the "fathers" who witnessed these acts but often failed to remain faithful.
The specific mention of "Zoan," an ancient and important city in Egypt (often identified with Tanis), grounds these wonders in a real, historical place. It signifies that God's powerful acts occurred in the heart of the enemy's land, demonstrating His sovereignty.