Historically, month names are names of moons (lunations, not necessarily full moons) in lunisolar calendars. The length of the table is 405 lunations (about 33 years). Two successive lunations take slightly more than 59 days. However, 19 uncorrected Julian years are a little longer than 235 lunations. Therefore, about 12.37 lunations (365.24 days divided by 29.53 days) occur in a tropical year. No prefixing number meant one, whereas the numbers two through six indicated the other lunations. So every 14 lunations there is a Full Moon nearest to perigee. Successive months (or lunations) are numbered from 1 to 12 within the Thai year. The lunations marking the middle of each half-year may also have been marked by festivals.