Greld is earth-like in most respects, although the animal life differs somewhat in that there is little varity in its details. It is said that life began here, but it is obvious to the scholar that some type of life evolved separately on each world. But it is certainly true that human life first evolved on this planet. It follows then that this is the most populated of all the worlds. So populated that the planet could not sustain life unless continuously supplied with food and other goods from the other worlds.
Because humans have lived on this world for so long (a estimate of 300,000 years of un-recorded history and 50,000 years of recorded history) the culture on this world is extremely advanced, and far beyond "medieval", although it is still feudal. Power is held in the hands of the nobility, but it was not always so. This world had its "fling with democracy" about 15,000 years ago, and found it less stable than their present system of a "guarded nobility". This phrase refers to the test that any ruling nobleman must undergo before being allowed access to political power. A panel of high level magicians reviews each prospective heir. By means of ESP, Detect Allignment, See Aura and other spells, their suitability for governing is determined. If a candidate is found to have weaknesses or mental/physical defects, the next born child within the House may take the test. Both men and women may rule if tests are positive, so inheritance may pass across family trees, but the name of the house within the Rolls of Nobility is not changed.
There are two moons circling this planet, and both of them are inhabited. This was accomplished through magical Tera-forming which began 12,000 years ago. Clerics using devices of airless breathing would cast as many "Create Water" and by the help of the Gods (and through the fervent prayers of many million Worshippers) they cast "Create Air" spells many time a day. After many hundreds of years of devotion on the life-less moon, there would be air enough for other men and animals to begin the population and foliation of the new world.
The planning for these worlds took many decades during which fierce political and scholarly battles were fought. As it all turned out, these moon-worlds are very different. Roon, the first of the moons to be inhabited, is still quite wild and the surface atmosphere is full of choking dust to this day. The second moon named "Klee" is much more pleasant. It is a veritable garden without which Greld would be unable to feed its many billions.