There are over 7000 languages that are used around the globe and they all belong to different regions and families. Every language has a different origin. It is difficult for researchers to determine which is the oldest language however one of the oldest written scripts that were found in Mesopotamia is called Cuneiform script and is predicted to be from 8th Millennium BC. Another script that is predicted to belong in the third Millennium BC is called the Sumerian script which also included funerary inscriptions. 
Even though Sign Languages and primitive sounds were the major modes of communication used earlier, linguists suggest that the age of a language can be appropriately measured based upon when its first text was created.
Here are some examples of the oldest languages as predicted by linguists:


1. Latin






Latin is said to have first appeared in the form of script in the 75 BC. It started somewhere close to the Italian Peninsula and gained its popularity throughout Rome. After that, the Roman empire chose Latin to be its formal language. Thus Latin became widespread in that region and gave birth to many other languages that are now very popular and spoken. Some of these languages include French, Italian,  Romanian, Spanish, Catalan, and Portuguese. Even now, it is the official language in Poland and the Vatican.


2.  Armenian






Armenian script was first noted in the 5th century and it was the translation of Bible. Originating somewhere within Europe, studies suggest that this language started somewhere in the 450 BC. Armenian is still the first language to almost 5 million people mainly located in Ukraine Russia, Iran and Georgia.


3. Korean






Korean language, that is spoken as of now was developed from Proto-Korean and  Old Korean. During the Legacy and time of the three kingdoms, old Korean was widespread. Due to the influence of China at those times, many old Korean scripts actually used Chinese characters which are still used in the existing Korean language.


4. Sanskrit 





It is said that Sanskrit is the father of all languages, especially within Europe. Another theory suggests that Sanskrit came from Tamil. The first Sanskrit texts and scripts are likely from 2000 BC. All traditional Hindu scriptures and the holy book for Hindus is written in Sanskrit. Despite less use of the language, it is termed as one of the official languages in India.


5. Greek






Greek has one of the longest histories and was first used in 1450 BC in Europe. Even now Greek is the main language for about 13 million people in Greece, Cyprus, and Albania. Greek language as a lot of significance as famous poets like Odyssey and Iliad wrote their poems in this language. A lot of scientific, mathematical, and astronomical works were written in Greek. Many documents about philosophy, such as the work of Aristotle and Plato were also written in Greek.