What is the meaning of "the voice of three continents and four rivers" in couplets?

Hakka ancestral temple culture has attracted much attention in Hakka culture, and Tang numbers and Tang couplets are indispensable parts of its ancestral temple culture. In the historical process of continuous southward migration, Hakka ancestors and their descendants, combined with the hardships of their ancestors' southward migration and settlement, sought their roots and missed their ancestors' psychological needs and spiritual demands after settling in Fujian, Guangdong, Jiangxi and Guangxi. Hakka people pay special attention to genealogy, ancestral halls and ancestor worship because they pay attention to ancestor worship and respect. The hall number and couplets of the ancestral hall can best express the feelings of Hakka people in remembering and carrying forward their ancestors. As the name of the ancestral hall, the hall number is a symbol of a surname. Generally, there are two names: one is taken from the birthplace of ancestors. Looking underground; Another is to commemorate the merits and demerits of the ancestors of an official street. It can be seen that the number of Tang Dynasty represents birth and lineage, history and honor. China traditional couplets are used, and the antithesis is neat and distinctive. Generally, there are special terms such as "family voice" and "peace in the world", which emphasize ancestral achievements and ancestral place names. The Central Plains region, especially Heluo region, is the ancestral home of most Hakka ancestors who moved south in the past. The records of historical books and many relics can prove this point from almost different angles, and the hall number and hall couplet are the most powerful and direct evidence. Mr. Deng Xunzhi, a Hakka research scholar, pointed out in the book "Hakka Origin": "Every Hakka surname must have a hall number, also called county number and place name, mostly Henan place names ... This means that even if Hakka people float in Wan Li, they still remember their ancestors and will never forget the hometown of the Central Plains." That's true. The Tang numbers and couplets of Hakka dialect clearly point out the origin of Hakka dialect, which proves that Hakka dialect really originated in the Central Plains and Heluo.