On 21 April 1930, Guillén sent Hughes the result of his inspiration, his book of poetry "Motivos de Son." The author wrote on the inside cover, “Al poeta Langston Hughes, querido amigo mío. Afectuosamente, Nicolás Guillén”. Although Hughes did not find an Afro-Cuban composer to work with, he created a lasting friendship with Guillén; it was based on their mutual respect and convictions about racial inequality. Cuba's dictatorial Gerardo Machado regime was overthrown in 1933, but political repression in the following years intensified. In 1936, with other editors of "Mediodía", Guillén was arrested on trumped-up charges, and spent some time in jail. In 1937 he joined the Communist Party and made his first trip abroad, attending a Congress of Writers and Artists in Spain. During his travels in the country, he covered Spain's Civil War as a magazine reporter. Guillén returned to Cuba via Guadeloupe. He stood as a Communist in the local elections of 1940. The following year he was refused a visa to enter the United States, but he travelled widely during the next two decades in South America, China and Europe. Guillén's poetry was increasingly becoming imbued with issues of cross-cultural Marxist dialectic. In 1953, he was prevented by the Fulgencio Batista government from re-entering Cuba after a trip to Chile and had to spend five years in exile. After the Cuban revolution of 1959, Guillen was welcomed back by Fidel Castro, the new president. In 1961 he was appointed as president of the "Unión Nacional de Escritores de Cuba," the National Cuban Writers' Union, serving for more than 25 years. He continued to write evocative and poignant poetry highlighting social conditions, such as "Problemas de Subdesarrollo" and "Dos Niños" (Two Children). He was considered the national poet of Cuba, who drew from its multicultural history and population for inspiration. Nicolás Guillén died in 1989 at age 87 of Parkinson's disease. He was buried in the Colon Cemetery, Havana.