There are in fact a number of languages with over 20 million speakers that have no standard written form. The main examples are the various Chinese varieties. Only Mandarin, Cantonese and to a far lesser degree Hokkien have a written tradition.
Leonese is one of the most obscure languages in the entire world- only being spoken by between 20,000 and 50,000 people, and only known by a handful more people! Like most other languages in Spain, Leonese too, is a romance language.
For example, Marathi is the official language of Maharashtra, while Ahirani, Wharadi, Konkani, and Malwani are its dialects. Several languages in India are spoken but do not have any script. In Karnataka, Kannada is the official language. Tulu is spoken in Karnataka but has no script.
The Inca, a technologically sophisticated culture that assembled the largest empire in the Western Hemisphere, have long been considered the only major Bronze Age civilization that failed to develop a system of writing—a puzzling shortcoming that nowadays is called the “Inca Paradox.”
The majority of the 3,500 languages and dialects in the world, some 3,000 in fact, are unwritten. Mexican Indians have over 100 unwritten languages and dialects for example, and India has over 1,000.
There are around 7,000 languages spoken in the world today. More than half of the world's languages have no written form.
Mandarin Chinese
Interestingly, the hardest language to learn is also the most widely spoken native language in the world. Mandarin Chinese is challenging for a number of reasons. First and foremost, the writing system is extremely difficult for English speakers (and anyone else) accustomed to the Latin alphabet.
Sumerian can be considered the first language in the world, according to Mondly. The oldest proof of written Sumerian was found on the Kish tablet in today's Iraq, dating back to approximately 3500 BC.
1 - Papua New Guinea: 840
Papua New Guinea is the world's most multilingual country, with a total of 840 languages spoken.
Latin is by far the most well-known dead language. Though it has been considered a dead language for centuries, it is still taught in school as an important way to understand many languages.
Ithkuil is an experimental constructed language created by John Quijada. It is designed to express more profound levels of human cognition briefly yet overtly and clearly, particularly about human categorization. It is a cross between an a priori philosophical and a logical language.
Current data states that there are only 7 remaining speakers of the language. Written records are available, such as a dictionary and several books that show the grammar and syntax of the Dumi language. Dumi is the world's least spoken language and one of the rarest.
Some have only one official language, such as Albania, France, Germany and Lithuania. Some have more than one official language such as Belarus, Belgium, Canada, Finland, Afghanistan, Paraguay, Bolivia, India, Switzerland, and South Africa.
The United States and India have the most total English speakers, with 306 million and 265 million, respectively. These are followed by Pakistan (104 million), the United Kingdom (68 million), and Nigeria (60 million).
Aramaic is best known as the language Jesus spoke. It is a Semitic language originating in the middle Euphrates. In 800-600 BC it spread from there to Syria and Mesopotamia. The oldest preserved inscriptions are from this period and written in Old Aramaic.
The Adamic language, according to Jewish tradition (as recorded in the midrashim) and some Christians, is the language spoken by Adam (and possibly Eve) in the Garden of Eden.
Across multiple sources, Mandarin Chinese is the number one language listed as the most challenging to learn. The Defense Language Institute Foreign Language Center puts Mandarin in Category IV, which is the list of the most difficult languages to learn for English speakers.
After the Hungarian grammar, the Finnish language has the most challenging grammar. It sounds and looks a bit similar to English because of its pronunciation and lettering. But the grammar makes it far more complicated than the English language.
Currently, there are 573 known extinct languages. These are languages that are no longer spoken or studied. Many were local dialects with no records of their alphabet or wording, and so are forever lost. Others were major languages of their time, but society and changing cultures left them behind.
Nepal's Kusunda language has no known origin and a number of quirks, like no words for "yes" or "no". It also has only one fluent speaker left, something linguists are racing to change.
Spanish is the second most widely spoken language globally in terms of native speakers. In addition, it is the most spoken of the Romance languages and the third most used on the internet.