How did geography influence the development of the byzantine empire?

It was right in the middle of the Bosporus, Black Sea and the Mediterranean Sea. So, all trade between North Africa, Asia and Europe, had to pass through the capital (Constantinople), causing the Byzantine Empire to become very wealthy due to taxes they charged between the trading.

nothing certain is known about what happened, but it seems that the country declined gradually, perhaps due to bad government, or, more likely, due to a series of bad harvests, which resulted in widespread and recurrent famine.