This puzzle was published on Eric Westbrook's 3D Calendar Crosswords site on the 15th March 2018 as an adjunct to the main March puzzle by Shark (grid by Chalicea). It is called the March Extra puzzle, set by Eclogue with a grid designed by Logogriph.
The Theme2018 is the 153rd anniversary of the births of Scandinavian composers Jean SIBELIUS (8 December 1865) and Carl NIELSEN (9 June 1865).
Thematic material appearing in the gridComposer surnames, plus examples of their works: FINLANDIA, KARELIA (Suite), EN SAGA and TAPIOLA (Sibelius) and SAUL AND DAVID and ALADDIN (Nielsen)
Further materialThe purple cells can be anagrammed to form the first names (CARL and JEAN)