Hin: झुन्झुनू jhun̄jhunū
‘Jhunjhar’s Town’ City/District, Rajasthan
From Jhunjhar or Jujhar Singh
This is an interesting one. The reduplication implies a repetitive rattle or ‘jingle-jangle [Hin: jhun-jhunā, ‘rattling toy’, ‘rattle’; Skt: jhaṇa-jhaṇāya, ‘tinkle’, ‘jingle’, ‘rattle’.] and it is so tempting to make a connection with bangles: this is one of the many cities in Rajasthan famous for making lac bangles, associated with the Manihar (Muslim) and Lakhera (Hindu) communities.
There is, however a rather more straightforward explanation: Jhunjhar or Jujhar Singh Nehra (1664-1730) was a Jat chieftain who defeated the Nawab ruler, Sadulla Khan. Unfortunately, he was assasinated by conspiring Rajputs soon after his Durbar. The town was renamed to commemorate his victory and his martyrdom.
Although any material can be used to make bangles, lac is the favourite in Rajasthan and is considered especially auspicious for brides and babies. The word lac [Skt: lākṣā ‘red dye’, ‘lac’] refers to both the cochineal insect and the scarlet resin they produce which is processed to make (shel)lac for sealing wax, varnish and bangles.
Jhunjhunu is also known as ‘City of Copper’ and Khetri Nagar in Jhunjhuna District is a major site for copper production.

Woman with a scarf and bangles, Rajasthan Christopher Michel