During the First and Second Waves of interstellar exploration and colonization, the Terran Mandate encountered a handful of sapient species also capable of interstellar travel. In contrast to the Mandate, the domain of each species had reached a sort of equilibrium. Internally, the politics, economy, culture, and population of each was quite dynamic and alive, but they had little interest in exploration or colonization. From the outside, they were quiescent. Even though they were all much smaller than at their greatest extent, there was no push to increase territory, and the total population was very stable, only growing by a few percentage points each century.
These species are known by a handful of different terms, "pre-Mandate species" being the most common. "Quiescent species" and "equipoise species" are also used, mostly by academics and intellectuals.
As a rising tide lifts all boats, the pre-Mandate species were swept up by the waves of human expansion and carried throughout the Mandate and frontier worlds. An enclave of every species can be found on most inhabited worlds and major settlements. Some worlds are dominated by humans, with other species all together comprising only 1% or 2% of the population. Other worlds are split more evenly between humans and one or two pre-Mandate species. A settlement dominated by a pre-Mandate species is uncommon, but there are typically two or three in every sector. A world without a majority species is often divided along species lines, but there are many cosmopolitan colonies with interspecies integration and equality. Note that these trends are sweeping generalizations. In short, anything is possible.
Note that robots were not a pre-Mandate species like the others. There was no robot nation with its own culture, politics, and so on. Robots are simply included here merely to make this a complete list of all sapient species, but there was no separate or independent robot civilization that was contacted by the Mandate. Many cultures have servile sapient robots, and many cultures consider sapient robots to be fully equal with biological sophonts.