` Ad
The nation of ` Ad was proverbial in their size, physical strength and power as well as the strength that came to them in the wake of their children. Holy Prophet Hud (علیہ السلام) was sent to them. Eventually, they were annihilated by the Divine punishment of a wind storm.
Fir'aun
This is the title of the Egyptian king (The Pharaoh) notorious for his tyranny.
Brothers of Lut
It means the community of the Prophet Lut (علیہ السلام) whose story is narrated several times in the Qur'an.