Hi Amer Naseem,
I have attached "Yocto project user's guide" which can be used to setup environment for imx yocto build. You can refer the packages which are required to build yocto from section 3.1 of attached user's guide.
by the way, I have generated for Ubuntu Desktop 16 and currently trying 18, it seems that section 3.1 could be complemented with information;
For Ubuntu 16.04 and 18.04
apply "Essential Yocto Project host packages",
then "i.MX layers host packages for a Ubuntu 14.04",
and finally invoke "sudo apt-get install curl"
For Ubuntu 18.04:
invoke also "sudo apt-get install python"
Hope it helps
"Yocto project user's guide" directed me to "Yocto Project Quick Start" which requires to install Python 3.4.0 or greater. Is version 3.4.0 for Phython or Python3 ? I think it is Phython3 because version number starts with numeral 3 ?