You can find some information about it here.

Going in detail over it is not important from CSS point of view. Such topics being outdated are not asked in paper generally.

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~Hamaray Lehjay Mein Ye Tawazan Barri Saoobat Ke Baad Aaya
~ Kai Mizajon Ke Dasht Dekhay; Kai Rawayyon ki Khaak Chhani~