This paper investigates the relationship between a song and its genre in thachingyi (great song), which also refers to Burmese classical songs. There are over one thousand songs listed under this category, and they are divided into approximately twenty different genres in song anthology publications.<br>Conventional literature has attempted to define genres according to their musical features or the origin of their names, and there have been no doubts with regard to the division of genres. According to these literatures, it is evident that the genres are distinct and almost any song can be classified under a certain genre. This opinion is based on the fact that many of the songs belonging to the same genre have the same melodies and therefore are similar to each other; further, all song anthology publications are segregated on the basis of the genres they belong to, and consequently, all songs can be categorized under a particular genre.<br>I have discussed the adequacy of genre divisions in song anthologies, which serves as a background for the perspective that genres have immovable boundaries. By analyzing palm-leaf and paper manuscripts, I have highlighted that during their inception, songs were not slotted into any particular genre.<br>It was only in 1870 that a manuscript was edited, which featured a compilation of song titles that were edited according to genres. Following this, all manuscripts and publications of songs began to include songs that were comprehensively edited and compiled according to their individual genres. Gradually, the genres for each song stabilized. However, even today, some songs can be categorized under two different genres. Therefore, I hypothesize that the genre of a song and its relationship with the song is not determined at the time of the song's inception.<br>There are some collimating marks that are used when composing or performing songs. A particular set of marks is said to define a certain genre; however, when performed, the marks and the genres of some songs are sometimes changed. Conventional literature assumes that these songs are exclusive to certain genres. However, as a result of genre divisions being imposed on songs, these songs are not exclusive to one genre but exist on the borderline between two genres. In addition, I believe that genres in thachingyi should be examined from the following two perspectives: the definition of certain genres and the relationship between a song and its genre. I also opine that the relationship between individual songs and their genres is not absolute.<br>Therefore, I shall now proceed to investigate the adequacy of genre divisions. There are five marks that are assumed as constituting a certain genre: (1) mode, (2) rhythmic patterns, (3) tunes that are frequently used in a certain genre, (4) a prelude that is fixed according to a certain genre, and (5) a postlude that is fixed according to a certain genre. There are some genres that are defined by their contents or forms of lyrics. However, there are also some songs, the marks of which deviate from those that are assumed to belong to a particular genre. I consider that it is these songs that highlight the blurred line separating one genre from another.<br>I have discussed some marks that are assumed to constitute classification under a certain genre. There are four modes consisting seven tones. The four modes are classified into two types based on their gapped structure. Garfias [1975] classified the hninlon tuning and aukpyan tuning modes as type I , and pale tuning and myinzain tuning as type II. Modes are assumed to be the most important mark defining a certain genre. Any conventional literature draws the relationship between a certain genre and the mode used to play songs from that genre. But a certain mode can be used to play a song belonging to not one but many genres. Therefore, it is impossible to define a genre by its mode. Becker [1968] discusse