Greeting Greyhawk fanatics. Today I'm going to take a wild stab at an esoteric topic I bet no one except perhaps Gary Gygax, Anne Brown and Lance Hawvermale have ever pondered: how many Rhennee are there in the Flanaess? Before I get into my boring research, a few caveats, one, I'm no expert on demographics. There is many D&D fans who have done way more in this department than me. Two, I'm only going to count the barge-folk Rhennee, not their land-born cousins, the ill-named Attloi. Lastly, I'm pulling together sources from a few disparate editions here, to arrive at an interesting conclusion. None of this fantastical population crunching should diminish your love of the Rhennee, instead I hope it enhances by making DMs and players take notice of this human ethnicity and give them a try in the future. Enjoy!
According to Gygax, in the Glossography, the Rhennee resemble Oeridians except they have darker, curlier hair and are shorter on average. They are wiry and strong and claim to have come to the Flanaess accidentally from a legendary homeland called Rhop. While their ancestors rode horses and lived in wagons, modern Rhennee culturally took to living in barges on the waters of the Nyr Dyv and its surrounding rivers by necessity of being immigrants in a hostile world.
Each Rhennee barge is home to a family averaging 33 people. The break down in the Glossography is as such: 1 chief, 2-4 guard, 13-24 "folk", 1-2 "advisors", 7-12 children and 1 "wise woman" (called Veth in 3rd Edition). Accordingly a barge inhabited by a Rhennee noble has a maximum compliment on his home barge, or 45 people.
In the Living Greyhawk Journal #2 article, The Way of the Lake by Lance Hawvermale, (buy it on DMsGuild) he writes that there are about 100 Rhennee nobles and roughly 5000 Rhennee total population. I postulate that this amount is low given what information is available from prior sources. 100 Nobles consisting of a family of 45 would already arrive our number of Rhenn-folk at 4500. Since there are clearly "common" Rhennee people who rally around these nobles in groups of 12-16 barges, the number must be higher!
Again taking averages, each Rhennee lord has about 13 common barges in his fleet. If each has an average family size of 33 as per Gygax's lists, then one noble family totals 574 Rhennee. And if we max out the over-all nobility of Rhennee at 100, then that easily gives us 57,400 Rhennee on the waters, or eleven times Hawvermale's initial estimate. Even with just 50 Rhennee nobles, the totals are impressive enough at 28,700. Take your pick of how many nobles there may be in the Flanaess.
Now of course, things happen on the Lake of Unknown Depths. Life is harsh in the World of Greyhawk. Perhaps the Rhennee have catastrophic deaths per year? Fine, but Gygax accounted for this, and later sources on the Rhennee omit this quite unfortunate fact:
"When needed, Rhennee steal young children to fill their ranks. Stolen children are raised as and become "natural" Rhennee. Similarly, outsiders who do some great service for the Rhennee are taken into the folk and sometimes accorded great status."
So yes, Rhennee are a culture, not a human bloodline necessarily. Players looking for an exotic background for their characters could theoretically make a Rhennee raised or adopted from virtually any playable race from tieflings to halflings.
According to Anne Brown in the Players Guide to Greyhawk (2E) the legendary Rhopans came in wagons to the Adri Forest and migrated west in CY 150. So, if we use the base timeline of Living Greyhawk CY 591, the Rhennee have been on Oerth for only about 440 years. That means depending on your source, 5000 to 57,000+ Rhennee exist after four and a half centuries of roaming the Flanaess (not counting Attloi). Now I'm no expert on Middle Ages style demographics, but either a small band of Rhennee accidentally rode into this world and prospered, or much like the Suel fleeing the Rain of Colorless Fire, they came en masse possibly through a magic gate or across a Fading Land as they are often found in this setting.
Despite my argument for more Rhennee, the inclination that there are 5000 or fewer is a good one. After all, why would 57,000 Rhennee need to stick to the waters, when they could just overwhelm and settle a place like the City of Greyhawk (that does have a Rhennee population) with nearly the same population. They could just as easily take over a lesser coastal town in the Bandit Kingdoms or anywhere with that kind of numbers. So, either the Rhennee don't have the numbers to establish their own domain, or their nobles choose to stay on the waters and hide their numbers to seem neither too weak nor too powerful. Well DMs, the decision is yours, I've made the case for both population levels. In summary, use Rhennee! They make helpful guides, traders, bards, fortune-tellers, villains and even heroes.