Are Faerûnian tieflings a people unto themselves?

Question

When it comes to tiefling population dynamics, the only relevant things the PHB has to say are that tieflings "are derived from human bloodlines," "subsist in small minorities," and "lack a homeland," and that some are "born into another culture." I can think of two primary ways to realize this in a setting:

1. Tieflings are primarily born to non-tiefling parents, and they primarily dwell in the communities of their parents, where tieflings are a minority, though some may seek each other out and form their own small communities. (A parallel could be drawn to the LGBT population in our world.)

   • Let's call this option "sparse."

2. There exist sizable communities that are majority tiefling, where tieflings marry tieflings and produce more tieflings, which is where most tieflings come from, though a new tiefling may occasionally be born to non-tiefling parents. (A parallel could be drawn to wizards and Muggle-borns in the Harry Potter universe.)

   • Let's call this option "dense."

This may just be due to flavor I absorbed in 3.5e, but I've always generally assumed that the "sparse" option is the more "correct" one. Now, this could vary by setting, so for this question, let's only focus on Faerûn/the Forgotten Realms.

I only know of the following further references to tiefling population dynamics in the rule books, both of which support the "sparse" option:

• The "Tiefling Parents" table on page 62 of Xanathar's Guide to Everything has entries for human + human, human + tiefling, tiefling + devil, and human + devil, yet no entry for tiefling + tiefling. Taken at face value, this suggests that tieflings cannot reproduce with each other, and thus the "dense" option is impossible.

• Page 119 of the Sword Coast Adventurer's Guide has the line "Beshaba has tiefling worshipers who consider the accident of their birth as a kind of cruel joke they have chosen to embrace," which can be read to mean that these tieflings have no parents who are also tieflings that might normalize tiefling-ness for them.

However, the "sparse" interpretation gets a wrench thrown into it by the video game Baldur's Gate 3 — set in Faerûn and (mostly) using 5e rules — which depicts a sizable (for a video game) community of tieflings, including tiefling siblings and tiefling couples with tiefling children, implying that the "dense" option is at work.

Hence, my question:

In official materials made for Fifth Edition other than Baldur's Gate 3, are the tieflings of the Forgotten Realms (primarily) described/depicted as "sparse" or "dense"?

"Official materials" primarily refers to official rule books, WotC-published adventures, the official novels, and probably whatever Ed Greenwood says. I don't know what other sources of lore there are for 5e Faerûn that might be considered "official."

Answer 1

Tieflings are generally depicted as "sparse"

There are as of this writing (and as far as I can ascertain) no published adventures or sourcebooks for 5th Edition that describe Tiefling communities, towns or nations similar to what you would describe as "dense".

The well documented entry on Tieflings in the Forgotten Realms Wiki likewise makes no mention of such communities and states

Being the result of fiendish interference with humans, tieflings had no true homeland and were found throughout Toril.

Baldur's Gate 3 has a tiefling community at the Druid Grove. They are described in the game as exiles from Elturel who had been blamed for the city being swallowed after that city had been restored from hell through the events depicted in Baldur's Gate: Descent into Avernus (reference: Baldur's Gate 3 Wiki). That means there must have such a tiefling community in Elturel to begin with, with full Tiefling families, like the ones we see in BG3. That adventure however does not describe any Tiefling community in Elturel, it only features individual Tiefling characters. So this is a new development by BG3.

As you yourself already have documented in detail in the question, in general in 5e Tieflings are depicted as an unusual occurrence, and not as a race that forms its own communities. So sparse is the norm.

However, because the story of BG3 was developed in collaboration with Wizards of the Coast, the content of the game (at least some storylines) is, like the original two Baldur's Gate games, apparently considered official Forgotten Realms canon. That means there is now at least one documented occurrence of such a "dense" community, with Tiefling families.