The nation of 'Aad were smart people but they ran the wrong system of life. They used to build vain monuments for show off. They had numerous slaves building for them high towers, forts and castles. The poor people were harshly treated by the elite and they split their society into two factions: the extremely rich and the extremely poor.
http://tinyurl.com/yckz95r A Thamud building in picture.
7:65 To the people of ‘Aad, We sent their brother, Hud. He said, “O My people! Serve God by serving His creation. You have no god beside Him. Do you not seek to live upright?”
7:66 The elite among his people who were disbelieving said, "Ah! We see that you are in folly, and we think that you are a liar.”
7:67 He said, "O My people! There is no folly in me. I am a Messenger from the Lord of the Worlds.
7:68 I convey to you the messages of my Lord, and I am a sincere and trustworthy adviser to you.
7:69 Why do you wonder that there has come to you a reminder from your Lord through a man from amongst you, to warn you? Recall that He made you successors to Noah’s people and gave you abundant power. Keep in mind God’s authority and blessings that you may continue to prosper.”
7:70 They said, "Have you come to us that we serve God alone and give up what our forefathers worshiped? Bring upon us what you threaten us with, if you are truthful.”
7:71 (‘Aad were a powerful community that had gone unjust. Since there is a Law of Respite for nations, they flourished and were unable to see the wrong thus far.) Hud said, "Your Lord’s Requital is already hovering over you. Do you argue with me about certain names that you and your forefathers have fabricated, whereas God never authorized them. Then wait for the consequences, and I am also waiting.” [53:23]
7:72 [The People of ‘Aad ruled a big empire in Arabia. However, they failed to heed the Prophet’s warning. Then hurricane winds annihilated them 41:16] We saved him and those with him by mercy from Us, and cut the root of those who denied Our messages and would not believe.
26:123 ‘Aad also rejected the Messengers.
26:124 When their brother Hud said to them, “Will you not seek to live upright?
26:125 I am a Messenger to you, worthy of your trust.
26:126 Be mindful of God and pay heed to me.
26:127 And no reward, whatsoever, do I ask for it. My reward rests with none but the Lord of the Worlds.
26:128 You build on every height monuments of vanity.
26:129 And you make for yourselves mighty castles; will you thus become immortal?
26:130 And you seize people cruelly, without any restraint. [Subjecting them into bondage to build these gorgeous structures for you]
26:131 Be mindful of God and heed me.
26:132 Be mindful of Him Who helped you with good things you know and the know-how and skills.
26:133 He Who has helped you with livestock and human resources.
26:134 And gardens and water springs.
26:135 Surely, I fear for you the requital of an awesome day.”
26:136 But they answered, "It is the same for us whether you counsel us or not.
26:137 This has been our life-style for generations.
26:138 And we shall never be doomed."
26:139 So, they rejected him and We destroyed them. Therein is a sign, even though most people are not believers (in the law of Just Recompense).
40:82 Have they not, then, journeyed about the earth and seen what happened in the end to those who lived before them? They were more numerous than these, and greater in power than these are, and stronger in the impact they left upon earth. Yet, all their achievements eventually failed to help them in the least.
40:83 For when their Messengers came to them with all evidence of the truth, they took delight in the knowledge they possessed. And the very thing they used to mock came on to pay a visit to them. [They took pride in their knowledge and skill and ridiculed the warnings of the Messengers that wrong systems crash down however smartly they might be run]
40:84 And then, as they saw Our strike, they cried, "We believe in God, the One God only and reject all that we used to associate with Him." [We will dismiss false ‘authorities’ and submit to God alone]
40:85 But their proclamation of faith could not help them, once they saw Our Blow. This is the law of God that has always applied to His servants. And so, there and then, lost were the rejecters of the changeless Divine laws.
89:6 Have you noted how your Lord dealt with ‘Aad? [They had refused to listen to their prophets on equitable treatment with the poor and violated human rights. 7:65-72]
89:7 Those whose capital was Iram, the city of towers and lofty mansions. [Iram were the generation of Iram son of Sam son of Noah. The capital of the tribe of ‘Aad bears the same name, Iram, and now lies buried in Al-Ahqaf, the Sand-dunes of Southern Arabia. 46:21]
89:8 The like of which (the towers and castles) were never built in other cities. [26:128-134]