In 19th century Russia, the 'Mighty Handful' were a group of what?

The Mighty Handful also known as The Five and The New Russian School, were five prominent 19th-century Russian composers who worked together to create a distinctly Russian classical music. Mily Balakirev (the leader), César Cui, Modest Mussorgsky, Nikolai Rimsky-Korsakov and Alexander Borodin all lived in Saint Petersburg, and collaborated from 1856 to 1870.

The formation of the group began in 1856, with the first meeting of Balakirev and César Cui. Modest Mussorgsky joined them in 1857, Nikolai Rimsky-Korsakov in 1861, and Alexander Borodin in 1862. All the composers in The Five were young men in 1862. Balakirev was 25, Cui 27, Mussorgsky 23, Borodin the eldest at 28, and Rimsky-Korsakov just 18. They were all self-trained amateurs. Borodin combined composing with a career in chemistry. Rimsky-Korsakov was a naval officer (he wrote his First Symphony on a three-year naval voyage circumnavigating the globe). Mussorgsky had been in the prestigious Preobrazhensky Regiment of the Imperial Guard, and then in the civil service before taking up music; even at the height of his career in the 1870s he was forced by the expense of his drinking habit to hold down a full-time job in the State Forestry Department.