He is often viewed as having intruded onto the throne due to the intrigues of his mother and thus taking the place of the rightful successor , his elder brother Ivan Sratsimir .
Bulgarian historians have had mostly negative assessments of Ivan Shishman .
Ivan Shishman is often viewed as having intruded onto the throne due to the intrigues of Ivan Shishman 's mother and thus taking the place of the rightful successor , his elder brother Ivan Sratsimir .
Bulgarian historians have had mostly negative assessments of Ivan Shishman .