Given that this pattern appears in several Georgian colors (the color purple is also just "lilac-color": იასამნისფერი / იასამნის ფერი), I'm sure they just used a different brown thing before coffee was common.

English didn't have the word "orange" until relatively recently (1500s) either. That's despite the word brown (which is the same colour in a different context) going back millenia.

Names change as language changes. It's hard to imagine Georgian didn't have a word for brown, but that would've been a completely different word that got displaced over time, like yellow-red was displaced by orange.

No idea about Georgian but that's not unusual - for example English didn't have color for orange for a long time. That's why you say "red hair" even though the color is orange.

There have been many authors who have claimed about various old languages that they lacked words for some colors, and "brown" is one of the most frequent colors about which such claims have been made.

I believe that most such claims, if not all, were wrong. The problem is that when reading an ancient text in which colors are mentioned it is very difficult to guess which is the color that is meant by some word and it frequently is difficult to even be sure that the word refers to a color and not to some other kind of property of an object.

There are very rare cases when the text says something like "this object is X like blood", so you can infer that X = "red", or "this object is Y like the sky", so you can infer that Y = "blue".

Brown is a color for which it is even rarer to find suitable comparisons in a text, from which the color can be inferred, than for colors like red, green or blue, which are typically compared to blood, grass and sky.

So when various authors have claimed that there was no word for "brown" in some old language, the truth was that they just were unable to find any word whose meaning could be determined with certainty to be "brown", in the preserved texts, even if there were plenty of words that most likely meant "brown".

Moreover, in nature there are many shades of brown, lighter or darker, more reddish or more yellowish, which is why in many languages there are multiple words for brown, which are derived from various things that have that particular shade of brown, e.g. words that mean coffee-brown, chestnut-brown, dry-earth brown, brown like the fur of certain animals, etc. Such words that identify a particular shade with reference to a familiar object have been renewed from time to time, in function of which objects have become more familiar or less familiar. After coffee became a very popular beverage, in many languages it has replaced whatever reference object was previously used for a dark brown.

As an example, many have claimed that Ancient Greek had no word for "brown". However, when reading Homer's Iliad and Odyssey, i.e. the oldest Greek texts except for the Mycenaean tablets, there already are a lot of places where there is no doubt that "brown" was meant by the word "aithono-". This is an adjective derived from the verb "to burn", and most dictionaries say that it means "burning". However, in the actual texts there are plenty of places where it does not mean "burning", but it means "burnt", more precisely "having the color of burnt wood", i.e. brown. This is not surprising. Another word used in the same way is "anthrakos", which can be used either for an object red like a burning ember (e.g. for red garnets or rubies) or for an object black like an extinguished ember (e.g. for charcoal or coal).

Actually brown in russian it's "bark-colored". bark = кора. Корица (cinnamon) is diminutive

You can also use "кофейный" (coffee-coloured) as synonym for "brown".

Celtic languages, and I believe Mayan, had a similar thing going on with blue and green. A lot of languages never distinguished orange from yellow really either.

Japanese has a word for green now 緑 (midori). Traffic lights use the word for blue for historical reasons