The main fact is the construction of the great wall by Theodosius II around Constantinople; completed in 450, has survived to this day, now its Turkish name is Rumeli-Gissar (Romei fortress). Constantinople was a trade crossroads from Europe to Asia, from the Mediterranean to the Black Sea, etc. Rome flourished while it was the center of a great power, and after the collapse of the Empire it lost its significance as a trading capital.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.