Due to their external similarity convergently acquired by strong selective pressures due to the identical habitat, they were occasionally believed to be close relatives. However, they belong to two well-distant families in the Sylvioidea, the "warbler-and-babbler" superfamily:
Cettia, the cettiid bush-warblers or typical bush-warblers, belong in the Cettiidae, an ancient sylvioid lineage related to long-tailed tits.[1]