You don't need to. Just go down focus interior and conquer/subject all the warlords and Mao. That will help you more in the long run.
If you want to do it just coz u like it. Basically it is like an election where you gain support in regions by completing decisions and once you have more support than the current ruler, you become China.
Check out this dev diary to learn more:https://forum.paradoxplaza.com/foru...v-diary-border-wars-the-last-warlord.1060469/
I personally rush straight for that focus and you really should win those wars quickly and smoothly. If you did focus interior but didn't declare war on them, you might be forced to join United front with communist China through Xian Incident (IRC, it is in the warlord focus tree the path that supports communist china)In my first attempt, I did this and the United Front still formed. But when during my second attempt, it didn't form and only Shaaxi and I were left to defend against Japan. So is there a way to form the United Front while focusing on the interior?
Also I noticed my stability decreasing every so often during the power struggle. What's causing the stability decrease - the warlords gaining support?
I feel like integrating the warlords and the "Foreign Threats" path shouldn't be mutually exclusive.