The terms Walser and Walliser are geographic; there is no linguistic divide. Specific Walser dialects can be traced to eastern or western dialects of Wallis canton. Conservative Walser dialects are more similar to the respective groups of Wallis dialects than to neighboring Walser dialects.
The German-speaking immigration to the Wallis started in the 8th century from the canton of Bern. There were presumably two different immigration routes that led to two main groups of Walliser dialects. In the twelfth or thirteenth century, the Walliser began to settle other parts of the Alps. These new settlements are known as Walser migration. In many of these settlements, people still speak Walser.
The dialects are difficult to understand for other Swiss Germans (called Üsserschwyzer 'outer Swiss' by the Walliser). This is because in the isolated valleys of the high mountains, Walser German has preserved many archaisms. The dialect of the Lötschental, for instance, preserved three distinct classes of weak verbs until the beginning of the 20th century. Walser German also shows linguistic innovations, such as the plural Tannu - Tannä (fir - firs), also found in the other Highest Alemannic dialects.
The total number of speakers in all countries is reported to be 20,000 to 40,000, including 10,000 to 20,000 speakers in Switzerland, out of a population of 7.5 million (1980 C. Buchli), 3,400 in Italy (1978 Fazzini), 1,300 in Liechtenstein (1995 C. Buchli), and 5,000 to 10,000 in Austria (1995 C. Buchli). (Source: www.ethnologue.com)