The origin of the Argumentative Nine Festival:

The Fuzhou people legend has it that the mother of the Buddhist Great Lohan, Meilian, who was plainly brutal, was punished for not having any rice for her soul after her death. The rice that Meilian sent to his mother every day would be eaten by the impermanent ghost pawns in the underworld. One day, Meilian sent a bowl of black sesame, glutinous rice with peanuts, red dates, cinnamon and other sweet black porridge cooked with brown sugar, the ghost pawns thought the porridge was dirty and refused to take it, so Meilian his mother used it to the meal. This day is also known as the Festival of Nine.

Customs:

With glutinous rice, brown sugar, plus peanuts, jujubes, water chestnuts, sesame, cinnamon, white fruit and other raw materials, cooked into a sweet porridge, used to worship ancestors or gifts to friends and relatives.

Expanded Information:

The Festival was originally called the "Lower Ninth Festival". Min custom, the first month is divided into "three nine", the first nine of the first month is called "on the nine", nineteen is called "in the nine", twenty-nine is called "the next nine ", and the first twenty-ninth day of the year is called "the next nine festival". Min miscellany" and other ancient books hold this view. And the 29th day of the first month of the new year for the last "nine" day, called it "after nine festival".

According to Fuzhou folklore, "nine" is a bad number, will bring poor luck. Therefore, on the 29th day of the first month, you have to cook congee and give it to others in order to drive the bad luck out of the house.

Baidu Encyclopedia-Argujiu Festival