Medieval Era has arrived!

At 125 AD, my civilization entered the Medieval Era. At this time, Mongolia with Genghis Khan is getting anxious to attack Persia and has begun asking on numerous occasions to stop all trades. This I would not allow do to our very good relationships through trading and expansion. This also makes me wary of Genghis Khan so I increased my soldiers and place them near the borders of our two territories as a precautionary strategy.
Also at this time, I had researched theology and was then able to discover Christianity. I had all cities within my civilization convert to Christianity, which allowed more culture to evolve and created more happiness among the people. Through the research of Monarchy, this was able to be a success. My continued expansion led me further northwest towards Germany. Here, I ran into the German leader who immediately wanted open borders. I agreed to peace but decided to refrain from open borders as, at this time, there was no benefit to my people. My culture continued to increase because of my new research in music, literature, and others. I also expanded my water territory by creating galleys that would allow me to move fast workers, settlers, and soldiers to other open territories. This allowed my civilization to further expand towards Rome and then to Egypt. I maintained peace with the Roman Empire and the leader of Egypt. My primary objective of trade with others continued to be my main focus, however, as new technology was being discovered and invented, my priorities became more detailed. I began to focus on trade, research, and more advanced technologies to secure my standing as the most powerful civilization thus far. I researched the alphabet early on as well as metal casting, which allowed my military to experience a growth in size and capability.
An unfortunate experience I have had with my largest city is the unhappiness they keep experiencing. Thus far, I have maintained a relative balance between the amount of happy verse unhappy and healthy verse unhealthy. However, I have experienced times when the people's unhappiness prevailed. This caused me to focus entirely on that one civilization to create certain buildings and structures to provide more health and happiness than others that would have benefited the civilization as a whole. Despite these obstacles, happiness was able to prevail in the city, as well as the others, enabling my civilization to become "Asoka the Glorious". As far as technology, wealth, and prosperity, I was well ahead of the others and am easily maintaining the number one position in all civilizations.
In 860 AD, I came across the Greeks and declared peace with Alexander the Great, as trade with them would prove to be very beneficial. Also at this time, I came across the Japanese Empire who was wary of me and visa versa. I maintained peace with them however, I remain uneasy about them due to their vast amount of war they are experiencing with other civilizations. They also have become annoyed with me early on as I am allied with Persia. As I move into the next era, I remain uneasy about Japan and have increased my military and technology in order to maintain my position within the situation.