I've got to call it this evening. It's quite late and sleep is catching up on me.
I've given you some thoughts on what to do. You have a good base here to work with.
You can expand out your land or stick with 5 to 6 core cities and launch and attack on Mongolia..or everyone else for that matter.
Start to think about where you want to go with this game, but for now do the things I've mentioned and settle at least 2 more cities.
If you don't have any urgent builds, you can always build "Reseach" and get to Currency or HR very fast.
Tech trading is important, but do so judiciously on this level. Backfill some old techs. You can even sell some of your old techs after currency, but don't give too much and certainly not the wrong thing to the wrong AI.
Avoid trading techs you have a monopoly on, especially on lower levels unless you absolutely have to have the target tech.
You can always post pics of a trade you plan to do so I can review it.