Requirement: Starting as a Zoroastrian custom nation with no more than 200 points and a maximum of 5 provinces, rekindle the royal fires (aka take the decision).
Province picking will be important at this point. Out of the required provinces, most of them are Persian cultures and only Khiva is non Persian culture. I picked the provinces in Tabarestan and three in Qara Qoyunlu. I did a mistake here, I should had choose provinces the Shrivan regions because they are European regions. It will be much faster to spread institution if I set my capital there. Also, most of my surrounding enemies are hordes, so I only picked mountainous provinces.
Choosing ideas: All of the surrounding provinces will be Muslim, Coptics or Orthodox. It will be quite difficult to convert new conquered regions with those -2/-1 local missionary strength. Hence, it is important to have increasing missionary strength in the tradition. Also, in the beginning, the biggest enemies will be the Timurids and Qara Qoyunlu, both of them have a larger quantity of army size. Moral boost in the tradition will be useful to fight against them in the early game.
In conclusion, I used the larger version Zorastrian Tabarestan. My national idea groups were defensive, economics, influence, administrative, offensive and trade by the time I get the achievement.
PS: I used Art of War, Common Sense, Conquest Paradise, El Dorado, Res Publica, Wealth of Nation and Women of History DLC and content packs for this game.