I completed this achievement today after only one attempt. I was mostly fortunate though not to be attacked by any of my neighbors, which was probably based on pure luck. Instead of focusing on my tiny nation, QQ declared war on AQ and the Timurids attacked Multan. By the time they were finished with those wars, I already had an alliance with the Mamluks in place to discourage anyone from attacking me (the alliance was not cheap though; I sent the Mamluks a large gift and took out about 10 loans to build up my army). If either nation had declared war, then the plan was to offer myself as a vassal, but it never really came to that.
One of difficult things about this start I haven't seen mentioned is that Tabarestan has a 60-year-old ruler and no legal heir. I spent 14 years in a regency council because the sultan died immediately after producing a child. That was a lot of valuable time wasted, because QQ already had two or three vassals by the time I could do anything about it. But once I emerged from the regency the first thing I did was declare war on QQ; the Mamluks joined me and made this a lot easier. I took two provinces for myself, released Iraq as a vassal, canceled QQ's vassalage over Shirvan, and returned a core to the Ottomans. That last thing made the Ottos friendly toward me, so I formed an alliance with them. Otherwise I couldn't have completed the achievement, because the Ottomans were allied with the Timurids. I got around their alliance by inviting the Ottomans into a separate war against Armenia, and then I attacked the Timurids myself. The Mamluks wouldn't join me because of the -1000 modifier for joining multiple wars. I didn't need them though, because even with the huge troop disparity the Timurids weren't willing to engage my army and I just sieged down the war goal. There was only one major battle all war (which for some reason gave me 10 war score). The Timurids gave in once I drove up their war exhaustion and revolts appeared in their provinces.
First war was mostly just to cancel their alliance with the Ottomans. I needed two more wars to take enough provinces to form Persia. I completed it by 1521.
One of difficult things about this start I haven't seen mentioned is that Tabarestan has a 60-year-old ruler and no legal heir. I spent 14 years in a regency council because the sultan died immediately after producing a child. That was a lot of valuable time wasted, because QQ already had two or three vassals by the time I could do anything about it. But once I emerged from the regency the first thing I did was declare war on QQ; the Mamluks joined me and made this a lot easier. I took two provinces for myself, released Iraq as a vassal, canceled QQ's vassalage over Shirvan, and returned a core to the Ottomans. That last thing made the Ottos friendly toward me, so I formed an alliance with them. Otherwise I couldn't have completed the achievement, because the Ottomans were allied with the Timurids. I got around their alliance by inviting the Ottomans into a separate war against Armenia, and then I attacked the Timurids myself. The Mamluks wouldn't join me because of the -1000 modifier for joining multiple wars. I didn't need them though, because even with the huge troop disparity the Timurids weren't willing to engage my army and I just sieged down the war goal. There was only one major battle all war (which for some reason gave me 10 war score). The Timurids gave in once I drove up their war exhaustion and revolts appeared in their provinces.
First war was mostly just to cancel their alliance with the Ottomans. I needed two more wars to take enough provinces to form Persia. I completed it by 1521.