Let Egypt come with gifts of precious metals^[e];
    let Ethiopia^[f] bring tribute to God.
³² Sing to God, you kingdoms of the earth.
    Sing praises to the Lord. Interlude
³³ Sing to the one who rides across the ancient heavens,
    his mighty voice thundering from the sky.
³⁴ Tell everyone about God’s power.
    His majesty shines down on Israel;
    his strength is mighty in the heavens.
³⁵ God is awesome in his sanctuary.
    The God of Israel gives power and strength to his people.

Praise be to God! Psalm 68:31-35

What is the role of singing to the Lord in worship.

Let Egypt come with gifts of precious metals;
    let Ethiopia bring tribute to God.
³² Sing to God, you kingdoms of the earth.
    Sing praises to the Lord. Interlude
³³ Sing to the one who rides across the ancient heavens,
    his mighty voice thundering from the sky.
³⁴ Tell everyone about God’s power.
    His majesty shines down on Israel;
    his strength is mighty in the heavens.
³⁵ God is awesome in his sanctuary.
    The God of Israel gives power and strength to his people.

Praise be to God! PSalm 68: 31-35

Why do you think Egypt and Ethiopia are mentioned specifically here?