Semitic Etymological Database
May be an Akkadism, see the discussion and cognates under Akk. taḫūmu 'border, territory'.
Cannot be separated from Akk. takiltu ‘a blue-purple wooľ, Hbr. tǝkēlät ‘a blueish or violet coloured purple wooľ, JPA toklā ‘purple wooľ, J CPA twklɁ ‘blue fabric’, Syr. tekltā ‘blue-purple colour’. Their futher etymology is unknown.