Psalms 120-134 are designated "Psalms of Ascents." As with much of the terminology of the Psalms, no one is entirely sure what this means. The best guess is that these psalms were used by pilgrims "going up" to Jerusalem. In the Bible, Jerusalem is always "up."
Psalm 120 is the prayer of an Israelite living uncomfortably among foreigners. Meshech and Kedar are nowhere near each other. Their use in verse 5 must be metaphorical.
Lutheran liturgical resources recommend Psalm 121 for use at funerals. It is a brief meditation on YHWH's protective care. The "hills" in verse one may be the location of threatening dangers or, on the contrary, the hills may be the source of the desired help, i.e. Zion. The image is not entirely clear but, this being poetry, it doesn't have to be.
For some reason I believe that I am familar with the first verse of Psalm 122 from some liturgical use:
I was glad when they said unto me
"Let us go up to the house of the Lord."
I can't seem to locate the liturgical context in which that verse was used, though. Can anyone help? The psalm, in its entirety, is for pilgrims arriving in Jerusalem. They pray for the city.
Psalm 123 is a prayer for mercy. The psalmist asks for relief from the "contempt of the proud."
Psalm 124 gives thanks for escape from dangers. If this is indeed a pilgrim psalm, then I think the dangers of travel in the ancient world might have been the occasion. I know the liturgical use of the psalm's final verse:
Our help is in the name of the Lord
Who made heaven and earth. (Psalm 124:8)
This verse was a part of the order for Confession from the old Service Book and Hymnal of the Lutheran Church.
Psalm 125 declares that those who are faithful to YHWH can no more be moved than could Mt. Zion. YHWH surrounds the faithful as the mountains surround Jerusalem. Commentators seem to think that the "scepter of wickedness" in verse 3 may refer to foreign rulers. Jerusalem certainly saw its share of those. But, as is usual with the Psalms, this conclusion is tentative at best.
The good old Septuagint translated the expression "A Psalm of Ascents" with a term that the New English Translation of the Septuagint renders "An Ode of the Steps."
Next: Psalms 126-132