This is the 1004th most frequent Turkish word.
kurduğu
"Kurduğu" means "that he/she/it established or set up."
In this sentence, "kurduğu" refers to something that Ali has established or constructed, specifically the bridge.
Ali'nin kurduğu köprü, köyleri birleştiriyor.
The bridge Ali built connects the villages.
Here, "kurduğu" refers to the company instituting or founding something, in this case, the tradition.
Bu, şirketin yıllar önce kurduğu bir gelenektir.
This is a tradition the company established years ago.
In this example, "kurduğu" relates to the act of creating or imagining, as per the context of his imaginary world.