Regional Stability

When the core four meet each other, there are initially no wars.  Despite the relatively aggressive cultures of humanity and the Yazirians, somehow everyone manages to get along (for the most part).<br /><br />Over the course of the timeline, many other aliens are introduced.  I was wondering if anyone had caused the introduction of new species to upset the balance of power in the region.  <br /><br />This does not necessarily mean war.  It could mean just enough to make things interesting.<br /><br />Likely candidates:  Humma, S'sessu<br /><br />