 The stability , however , was not to last . Mysore 's expansions had been based on unstable alliances . When the alliances began to unravel , as they did during the next half century , political decay set in , presided over inevitably by pageant kings . The Mughal governor , Nawab of Arcot , in a display of the still far @-@ flung reach of a declining Mughal empire , raided the Mysore capital , Seringapatam , to collect unpaid taxes . The neighbouring Raja of Coorg began a war of attrition with Mysore over western territory . Soon , the Maratha empire invaded again and exacted more concessions of territory . In the chaotic last decade of this period , a little @-@ known Muslim cavalryman , Haidar Ali , seized power in Mysore . Under him , in the decades following , Mysore was to expand again . It was to do so prodigiously to match in size southern India itself . It was also to pose the last serious threat to the new rising power on the subcontinent , the English East India Company . 
