If the din were at the Pleiades, even then a person from Persia would have taken hold of it, or one amongst the Persian descent would have surely found it.  

قَالَ رَسُولُ اللَّهِ ﷺ لَوْ كَانَ الدِّينُ عِنْدَ الثُّرَيَّا لَذَهَبَ بِهِ رَجُلٌ مِنْ فَارِسَ أَوْ قَالَ مِنْ أَبْنَاءِ فَارِسَ حَتَّى يَتَنَاوَلَهُ  

We were sitting in the company of Allah's Apostle ﷺ that Sura al-Jumu'a was revealed to him and when he recited (these words):" Others from amongst them who have not yet joined them," a person amongst them (those who were sitting there) said: Messenger of Allah! But Allah's Apostle ﷺ made no reply, until he questioned him once, twice or thrice. And there was amongst us Salman the Persian. The Apostle of Allah ﷺ placed his hand on Salman and then said: Even if faith were near the Pleiades, a man from amongst these would surely find it.  

كُنَّا جُلُوسًا عِنْدَ النَّبِيِّ ﷺ إِذْ نَزَلَتْ عَلَيْهِ سُورَةُ الْجُمُعَةِ فَلَمَّا قَرَأَ { وَآخَرِينَ مِنْهُمْ لَمَّا يَلْحَقُوا بِهِمْ} قَالَ رَجُلٌ مَنْ هَؤُلاَءِ يَا رَسُولَ اللَّهِ فَلَمْ يُرَاجِعْهُ النَّبِيُّ ﷺ حَتَّى سَأَلَهُ مَرَّةً أَوْ مَرَّتَيْنِ أَوْ ثَلاَثًا قَالَ وَفِينَا سَلْمَانُ الْفَارِسِيُّ قَالَ فَوَضَعَ النَّبِيُّ ﷺ يَدَهُ عَلَى سَلْمَانَ ثُمَّ قَالَ لَوْ كَانَ الإِيمَانُ عِنْدَ الثُّرَيَّا لَنَالَهُ رِجَالٌ مِنْ هَؤُلاَءِ