This made me think of the structure of haplogroup J2, its full of bottlenecks, most of them expand in the metal age:
J-M205 , +110 snp's , TMRCA = 6000 ybp.
J-L283 , +61 snp's , TMRCA = 6000 ybp.
J-PF4993, +35 snp's , TMRCA = 5800 ybp.
J-Y14434, +29 snp's , TMRCA = 4700 ybp.
J-Z7308, +33 snp's...