Isn't Monday the first day of the week?

According to scholar An Chi, the way Vietnamese uses terms like "second," "third," etc., is influenced by Portuguese, where Sunday is considered the first day of the week.

Many people assume Monday is the first day of the work week, but traditionally in Vietnamese, Sunday is the first day of the week.

In his book *Eastern Stories, Western Stories* , scholar An Chi explains that the way modern Vietnamese names the days of the week as "Monday, Tuesday..." is influenced by Portuguese. According to him, the Portuguese called Sunday " domingo" —the first day of the week—while the following days were respectively called "Monday market day," "Tuesday market day," and so on.

Specifically, Portuguese uses names such as segunda feira (second market), terça feira (third market), quarta feira (fourth market), quinta feira (fifth market), and sexta feira (sixth market). These names originate from medieval Latin.

According to scholar An Chi, the Vietnamese language has "closely followed" this system by referring to the days from Sunday to Friday. Only Sabado – which originated from the Jewish Sabbath – was changed to "Saturday" to better suit Vietnamese culture.

This is also the reason why the second day isn't called "first." In the traditional Western-influenced way of counting, Sunday is already considered the first day, so the following day is called "Monday."

Beyond reflecting linguistic exchange, the way days of the week are named also reveals the historical traces of cultural contact between Vietnam and the West from centuries ago.

Source: https://znews.vn/thu-hai-khong-phai-ngay-dau-tuan-post1654003.html