In the early days of interstellar commerce in the Zulu Sector, there were no widely available translation devices, so it was common for traders to learn the native languages of the systems they did business in. However, even a grasp of a system's language did not guarantee a grasp of its culture, and many traders found themselves getting in trouble over simple misunderstandings. For this reason, many of them decided to develop culturally neutral languages that they could use for conducting business. Gradually, these various languages merged together, forming the basis for what is now known as Unilang.
Unilang has expanded from its origin as a simple trading language to the common language of all spacefaring races. It is the official language of the CIS by law, and is also the de facto standard language of most multispecies colonies and space stations. In fact, many beings born away from their species' homeworlds consider Unilang to be their primary language.