It is a possibility to delay war with Sassanids when I am playing as Eastern Roman Empire?

[Fryguis]

I am playing in TW: Attila with FotE as Eastern Roman Empire (very hard difficulty level in campaign and normal difficulty level in battles). Sassanid Empire declared war to me at 403 year. War with them is a nightmare. When I crushed one Sassanid's army they have three armies on it's place. They declared war to me too early. So I started ERE campaign again. I gave them money gifts but still they were hostile to me. They didn't want to trade with me though money gifts. Whatever I wouldn't do they are hostile to me and earlier or later declared war to me. I decided to play as ERE again from the beggining on very hard difficulty level in campaign and normal difficulty level in battles also. What I have to do to improve diplomatic relations with Sassanids from the begining of campaign and secure my east border? What I have to do to have trade agreement with Sassanids and delay war with them as long as it is possible, for example to 425 year or longer?

[Cgma]

What I have to do to have trade agreement with Sassanids and delay war with them as long as it is possible, for example to 425 year or longer?

Just declare war vs. White Huns. Sassanids even pay you for if you negotiate well.