We recently received a mail from a user from India complaining that one of our accredited language, Tamil (Sri Lanka) — ta-LK —, was named this way.
This user argued that as Tamil language originated from India, it should therefore be named Tamil (India).

This is what we replied to this user and we thought that this was worth sharing with the community.

Joomla!™ project is not concerned by the origin or nationality of various languages or dialects.
We can have variations of a said language depending on countries, or even regions, where they are used.

For example, we could have French (France), French (Canada), French (Switzerland), French (Senegal), etc.
We have already Portuguese (Portugal) and Portuguese (Brazil) as well as English (GB) and English (US).

We have been recently contacted by a volunteer who wants to make a more standardized Tamil pack aimed at Tamil Nadu and Tamil Eelam (India). We will welcome his work when done. His pack will surely be named ta-IN.
Same for Urdu where we have a Urdu (Pakistan) pack and would accept an Indian or Fiji Urdu pack.

On the other hand, our German-speaking Translation Teams recently united and now propose one single German language pack for Germany, Austria and Switzerland as they decided that the differences were not worth the extra work, specially concerning the type of semantics used in Joomla!.

Joomla! follows International naming conventions for language names, first part of the tag being the language ISO code, second part being a country ISO code.

This is why, for example, and although the Arabic language used in various Arabic-speaking countries is exactly the same language (Classic Arabic), our Arabic Translation Team had to use a country ISO code in the tag. They chose a country where the coordinator lives (Algeria, which gave ar-DZ), but it could have been Egypt or Syria or any other country in this case.
They did not have to choose Saudi Arabia or Yemen or any Emirates, although Arabic is originated, centuries ago, from the Arabic Peninsula.

The only language we have and could not add an existing ISO country code is Esperanto, as this language is by nature international. We decided to name it eo-XX.

We hope this clarifies Joomla!™ project policies on that matter.