Village Twinning is a form of brotherhood between villages, the purpose is for the villages to support each other in life such as: building dikes, building roads, fighting robbers, fighting against invaders..., hierarchical classification and treat each other as brothers. In Cổ Loa, this custom is very popular, also known as "beating friends" (making friends), "beating strips".

Cổ Loa village twinned with the villages of Quậy, Đông Trù, Đông Tảo, Hội Phụ, Tam Trảo ... Legend has it that when Thuc Phan An Duong Vuong chose the land to build capital, he had to move Quậy village to the lowland (Liên Hà commune today) so Cổ Loa village and Quậy village are now twinned. When building the communal house, Cổ Loa villagers had to buy wood from other areas and crossing the villages of Đông Trù, Đông Tảo, Hội Phụ, Tam Trảo, they destroyed the rice, so they twinned with them. The annual festival usually invites these villages. In addition, the hamlets in Cổ Loa village can also twin each other, such as: Chùa hamlet (eldest brother) twinning with Lan Trì (second-eldest brother), Nhồi hamlet, Hương hamlet, Vang hamlet, Mít hamlet; the group of Chùa, Mít and Hương hamlets joined together is called "three hamlets"; Gà village made friends with Lan Trì, Dõng Trên, Dõng Dưới; previously, Hương hamlet was twinned with Xuân Dực, later only between hamlets in Cổ Loa village...

Associated with village twinning is feasting in January and February. Banquet must have 8 bowls, 8 plates. The place is usually communal house (twinning between villages) and “điếm” (hamlet guardrooms) (twinning between hamlets). Villages often organize banquets and invite each other to participate. Particularly in the banquet of Gà hamlet and Lan Trì hamlet, usually only young people, the elderly do not come, but Gà village has to send a representative delegation to bring the meal. While feasting, there may be a custom of singing in response (“hát ống”), “tuồng”, or “hát ả đào” (go to a vietnamese geisha house).