What do you mean "Hainan is lost"?

I remember that the year I went to Kangda University coincided with the smashing of the counter-revolutionary clique of the Gang of Four. Celebration parades are everywhere in the street, colorful flags are flying and gongs and drums are loud. Of course, such an occasion can't blind us silly children. Children from all our buildings and courtyards, led by older children, fought for the pink flag dropped by the parade. Inevitably, there was some friction, and a group of people in other buildings shouted at us, "Hainan lost" and went back. Not to be outdone, we responded loudly to "the bully here" under the leadership of the older children. Although I didn't understand what the two sides were shouting at that time, I still vaguely understood the meaning, probably that our two groups are descendants of two different places. Later, at family gatherings on holidays, the elders often told us that "Hainan lost" meant that those people here laughed at us Shandong people who had left their homes and traveled across the ocean. From the northeast to the south, to the south of the sea, that is where our ancestors were raised-"the hometown of Shandong". You are probably descendants of the third and fourth generations of "going to the East". Later, as I grew up, I began to understand the meaning of "Hainan lost". At that time, our ancestors sailed across Bohai Bay in a small sampan or other people's boat and came to Dalian to earn a living and support their families. Because Shandong is in the south of the sea, these Shandong people who come to Dalian to make a living have a nickname: "Hainan lost". When crowds of Shandong people threw themselves at each other from Hainan, Shandong became their hometown and Dalian became their new home. Since then, I have deeply buried the memory of being a "Shandong native" in my young mind and my yearning for the mysterious land that once raised our ancestors.