To add to what DaveMcW says - alliances are effective. Note that the AI is not particularly good at fighting on two fronts, so getting an alliance with a civ that borders the one you're against is a good idea. For example, the chinese in this game could be an effective ally.
Firstly, the good points are that you've got a decent core established, One thing that is really in your favour is that the Mongols have no horses, because you settled on 'their' source - great move! This means that you will not be facing/have faced Keshiks, and in the early middle-ages, knights (if you can keep the mongols from trading for them). I note that you haven't hooked-up any of yours. Horsemen would have been a good early attacker (if you could attack with them before the mongols got to the middle ages and got pikes).
I see that you have a lot of temples - yes, they are cheap, but as has been said above, the luxury slider is better for keeping people happy. In despotism, the shields are better invested in military police.
If you look at your cities, you should look at ways to improve the shields per turn. If you take Kyoto for example, you are producing 7 shields per turn. This means that you get one sword every 5 turns - if you can increase shields by just one / turn, this means you get one every 4 turns. If you can increase it to 10/turn, that's one every 3 turns! Look at what can be done in all cities.
It appears that your governers are emphasising food. Something like Osaka is size 5, yet only producing a couple of shields / turn - start working some forests to get more shields.
In terms of research, you could consider shutting-down research to generate cash. This can result in loads of excess cash to buy techs - at diety (and especially on such a crowded world), self-research is often not worthwhile.