The Ancient Space Age refers to a period of several centuries that took place several millennia ago (roughly 200 BC to 300 AD, give or take a century), during which a number of planets made contact and interacted. Its participants included Calpha, Earth, Epsilon, and Zeta (modern Carribia). It is known that Earth, Epsilon, and Zeta were at the time named according to a convention using the Greek alphabet, with Earth's name being Gamma (the first letter in the Greek word for earth). It is suspected that Calpha was originally named Alpha, and it is unknown what planets went by the names Beta or Delta. Exonia is a likely participant or at least recipient of Ancient Space Age travelers, since some of its wildlife are almost certainly descended from species on other participant planets. Galg and Galgam are included as a possible participant for the same reasons, though with less strong evidence.
Travel between these planets was likely possible due to wormholes, the same phenomenon used for modern interplanetary space travel. There were probably wormholes in orbit around the planets, allowing them to traverse galactic distances using only the time and energy required to enter and exit low-Earth (or other planet) orbit. Still, even low orbit is beyond the reasonable capabilities of even advanced civilizations at the time, especially on Earth due to the lack of any evidence for the many technologies required for modern rocket launches. This has led to the speculation that there were superpowered individuals at the time whose abilities, together with the most advanced technology of the time, enabled space travel. It is possible that some planets also used the Quamethysphere to power technologies that allowed for easier escape from gravity or even for direct wormhole creation, since the Quamethysphere played a significant role in the end of the Ancient Space Age.
The use of the Greek alphabet indicates that Earth played a prominent role in Ancient Space Age interactions. It is suspected that the participants were not entire civilizations but rather highly technologically advanced groups within civilizations, probably remnants of much older advanced civilizations. It seems that space travel on Earth was initiated by inhabitants of Crete (familiar with the Greek language) who were descended from whatever civilization inspired the Atlantis legends. They were joined by Vedic Indians descended from the Indus Valley Civilization, as well as a savvy group of Mayans.
The Ancient Space Age began rather gradually as various groups on various planets noticed the nearby wormholes, developed technology or other means to reach them, and made contact with other groups, including the usual setbacks of language learning, disease exchange, and general distrust of another species. After a century or two, though, relations appear to have been fairly civil among the various planets, or at least the groups who actually did any space travel, with technology, language, food, and livestock being exchanged freely and for mutual benefit. Since species on Earth fit fairly well into a basic family tree, it is unknown whether alien animals were not introduced for some reason, or were introduced and either died out, have not been rediscovered, or are known but not recognized as alien. On other planets, however, Earth-descended wildlife has been documented decisively, including some of the fish on Calpha, the (heavily mutated) giant spiders on Exonia, and even some humans that remained on Epsilon.
The era ended more abruptly due to a conflict over the Quamethysphere. It is not yet clear what all the sphere had been used for previously, and the course of events of the conflict are also vague. What is clear is that Zeta (modern Carribia) was considered by the others to be the instigator of the conflict and thoroughly in the wrong, resulting in the planet's civilization being nearly destroyed. This also resulted in the loss of the Quamethysphere and the closing of the wormholes soon after (leading some to believe that the wormholes were opened and sustained by the sphere's proximity along some higher-dimensional measure). This prevented any further contact between participant planets, since they were now hundreds to tens of thousands of light-years apart. On Earth, the civilizations that participated in this space age either gradually died out or were assimilated into their surrounding cultures, sharing little or no direct knowledge of the past events with their countrymen (though their inventive and pioneering spirit may have had an influence in following cultural revivals).