Salam, My question is if someone is born in such a place like in some desert of Africa or somewhere in a village in Fiji. I mean in such a place where he doesn't even know about Islam, and his parents too don't know about Islam. And he dies without knowing about his true Lord, i.e., Allah. How can he be blamed tomorrow for not becoming a Muslim?

Thank you for your question and for contacting Ask About Islam.
I would like to bring to your attention something basic which is that Muslim history has brought to the world the most sophisticated intellectual production the world has ever seen.
Those scholars are not only amazing thinkers who brilliantly and creatively mastered many sciences paying unequivocal attention to Islamic bases and ethos, they were also righteous souls who achieved what they achieved by piety and closeness to the God. Few examples of these disciplines are the works of theology and jurisprudence.

Now in relation to your question, which is a sensitive one since it deals with a core theological endeavourer, I will base my answer on the works of major acclaimed scholars. And being a student of sacred knowledge, I will try to restrict my answer to their views, without any creative thinking.
What you should know to begin with is that the issue has been dealt with by many Muslim scholars and from many theological schools. First, there is a theological technical term which deals with the subject matter, "ahl al-fitrah", the people who existed during the time of two messengers, without having heard of them.
Following the two orthodox schools of theology, the Ashari and Maturidi, there are two opinions. The respected opinion of Maturidi’s believe that while the stipulations to follow the law of certain message is dropped from such people, they nonetheless have to believe in the oneness of God, most-High. This is because human intellect on its own is perfectly capable of reaching this end of belief.
For the Asharis, as stated by the highest seat of Sunni Islam scholarship and its mouthpiece, Dar al Ifta, the ruling is such people who existed before Prophet Muhammad (peace be upon him) and after Prophet Jesus (peace be upon him), are saved from Hellfire.
This is the opinion of many revered and notable scholars, including, from the early generations, Imam Al-Qurtubi, and from the latter generations from this theological school are the eminent scholars; Imam Al-Nawawi, Ibn Hajar, Al-Manawi, and Al-Suyuti, among scores of others.
Proofs for adopting this position are based on many evidences including:

{...We never punish until we have sent a messenger.} (Al-Israa' 17:15);

{And how many a community have We destroyed that was thankless for its means of livelihood! And yonder are their dwellings, which have not been inhabited after them save a little. And We, even We, were the inheritors.} (Al-Qasas 28:58);


{As it would burst with rage. Whenever a (fresh) host is flung therein the wardens thereof ask them: Came there unto you no warner? [i.e. a messenger].} (Al-Mulk 67:8)

Now, many scholars, including Imam Al-Ghazali in his momentous work Faysal al-Tafriqah (On the Boundaries of Theological Tolerance in Islam, translated with an important introduction by Sherman Jackson) believe that the same ruling of ahl al fitrah, from the first school, applies to anyone at any time, who either did not hear about or only found distorted views about Islam, including ones in modern day urban life even who are surrounded by storms of distorted and twisted views of Islam. This directly answers your question.

Finally, we always have to remember something that God, majestic in His praise, His mercy, as He ascribed to His transcendent self, is above His justice.

This means only that all humanity will be dealt with from this standpoint, that even the torture of the most deniers of the unity and the existence of God, despite many proofs and human experience that elude to the contrary of their beliefs, in itself, this is a form of mercy.

I hope this answers your question. Please keep in touch.