Psalm 120

I wonder if the psalmist knew someone from Meshech and Kedar? Or was he only speaking in terms of rumors. Were they a warrior people? Or were they like the first century Cretans; "Cretans are always liars, wicked beasts, and lazy gluttons." (Titus 1:13). What was it about those people from Meshech and Kedar that turned off this psalmist. In knowing their traits I have a better understanding of what I need to avoid.
Stuart