Prove to me ancient Greeks didn't know how to breakdance. You can't.

"Finally, the crucial day came on which the marriage [of his daughter] was to be announced and Kleisthenes was to say whom he chose out of all the suitors.... When they rose from dinner, the suitors held a competition among themselves in musicianship and table-talk. The drinking went on and Hippokleides was winning easily; but now he ordered the flautist to play him a tune and when the man obeyed he danced to it. No doubt he danced to his own satisfaction, but when Kleisthenes saw him he took it rather ill. Hippokleides now paused for a bit, but then ordered a table to be brought and, when it came first danced Lakonian and then Attic dances on it and finally put his head on the table and danced with his legs in the air. Kleisthenes, during the first and second dances, had been repelled by the thought that Hippokleides with his dancing and his lack of self-respect might be his son-in-law; but he had restrained himself, wishing to avoid an outburst against him; but when he saw him dancing with his legs in the air he could hold himself back no longer and said, 'Son of Teisandros, you have danced away your marriage.' And Hippokleides simply replied, 'Hippokleides does not care,' which has become a saying."

(Herodotus, VI. 129-130)